From 9ab2d4db39bc951104642ab1a6f27ce32b7741a6 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Thu, 6 Dec 2018 13:32:19 +0200
Subject: [PATCH 001/108] ENH: fill_value argument for shift

---
 pandas/core/arrays/datetimelike.py     |  6 ++---
 pandas/core/frame.py                   |  4 ++--
 pandas/core/generic.py                 |  8 +++----
 pandas/core/internals/blocks.py        |  4 ++--
 pandas/core/series.py                  |  4 ++--
 pandas/tests/series/test_timeseries.py | 31 ++++++++++++++++++++++++++
 6 files changed, 44 insertions(+), 13 deletions(-)

diff --git a/pandas/core/arrays/datetimelike.py b/pandas/core/arrays/datetimelike.py
index 45eec41e498d1..a77faabd131ae 100644
--- a/pandas/core/arrays/datetimelike.py
+++ b/pandas/core/arrays/datetimelike.py
@@ -780,7 +780,7 @@ def _addsub_offset_array(self, other, op):
         return self._from_sequence(res_values)
 
     @deprecate_kwarg(old_arg_name='n', new_arg_name='periods')
-    def shift(self, periods, freq=None):
+    def shift(self, periods, freq=None, fill_value=np.nan):
         """
         Shift index by desired number of time frequency increments.
 
@@ -810,9 +810,9 @@ def shift(self, periods, freq=None):
         Index.shift : Shift values of Index.
         PeriodIndex.shift : Shift values of PeriodIndex.
         """
-        return self._time_shift(periods=periods, freq=freq)
+        return self._time_shift(periods=periods, freq=freq, fill_value=np.nan)
 
-    def _time_shift(self, periods, freq=None):
+    def _time_shift(self, periods, freq=None, fill_value=np.nan):
         """
         Shift each value by `periods`.
 
diff --git a/pandas/core/frame.py b/pandas/core/frame.py
index 2a8d58b8867b7..a6bc6226bda89 100644
--- a/pandas/core/frame.py
+++ b/pandas/core/frame.py
@@ -3867,9 +3867,9 @@ def replace(self, to_replace=None, value=None, inplace=False, limit=None,
                                               method=method)
 
     @Appender(_shared_docs['shift'] % _shared_doc_kwargs)
-    def shift(self, periods=1, freq=None, axis=0):
+    def shift(self, periods=1, freq=None, axis=0, fill_value=np.nan):
         return super(DataFrame, self).shift(periods=periods, freq=freq,
-                                            axis=axis)
+                                            axis=axis, fill_value=fill_value)
 
     def set_index(self, keys, drop=True, append=False, inplace=False,
                   verify_integrity=False):
diff --git a/pandas/core/generic.py b/pandas/core/generic.py
index b3cb5c3be67f9..3eafc137c527f 100644
--- a/pandas/core/generic.py
+++ b/pandas/core/generic.py
@@ -8868,15 +8868,15 @@ def mask(self, cond, other=np.nan, inplace=False, axis=None, level=None,
     """)
 
     @Appender(_shared_docs['shift'] % _shared_doc_kwargs)
-    def shift(self, periods=1, freq=None, axis=0):
+    def shift(self, periods=1, freq=None, axis=0, fill_value=np.nan):
         if periods == 0:
             return self.copy()
 
         block_axis = self._get_block_manager_axis(axis)
         if freq is None:
-            new_data = self._data.shift(periods=periods, axis=block_axis)
+            new_data = self._data.shift(periods=periods, axis=block_axis, fill_value=fill_value)
         else:
-            return self.tshift(periods, freq)
+            return self.tshift(periods, freq, fill_value=fill_value)
 
         return self._constructor(new_data).__finalize__(self)
 
@@ -8916,7 +8916,7 @@ def slice_shift(self, periods=1, axis=0):
 
         return new_obj.__finalize__(self)
 
-    def tshift(self, periods=1, freq=None, axis=0):
+    def tshift(self, periods=1, freq=None, axis=0, fill_value=np.nan):
         """
         Shift the time index, using the index's frequency if available.
 
diff --git a/pandas/core/internals/blocks.py b/pandas/core/internals/blocks.py
index 9c2d4cd5729d2..e2c2c884c7987 100644
--- a/pandas/core/internals/blocks.py
+++ b/pandas/core/internals/blocks.py
@@ -1260,12 +1260,12 @@ def diff(self, n, axis=1):
         new_values = algos.diff(self.values, n, axis=axis)
         return [self.make_block(values=new_values)]
 
-    def shift(self, periods, axis=0):
+    def shift(self, periods, axis=0, fill_value=np.nan):
         """ shift the block by periods, possibly upcast """
 
         # convert integer to float if necessary. need to do a lot more than
         # that, handle boolean etc also
-        new_values, fill_value = maybe_upcast(self.values)
+        new_values, fill_value = maybe_upcast(self.values, fill_value)
 
         # make sure array sent to np.roll is c_contiguous
         f_ordered = new_values.flags.f_contiguous
diff --git a/pandas/core/series.py b/pandas/core/series.py
index 6d951a7a5228a..197c2f304700a 100644
--- a/pandas/core/series.py
+++ b/pandas/core/series.py
@@ -3714,8 +3714,8 @@ def replace(self, to_replace=None, value=None, inplace=False, limit=None,
                                            regex=regex, method=method)
 
     @Appender(generic._shared_docs['shift'] % _shared_doc_kwargs)
-    def shift(self, periods=1, freq=None, axis=0):
-        return super(Series, self).shift(periods=periods, freq=freq, axis=axis)
+    def shift(self, periods=1, freq=None, axis=0, fill_value=np.nan):
+        return super(Series, self).shift(periods=periods, freq=freq, axis=axis, fill_value=fill_value)
 
     def reindex_axis(self, labels, axis=0, **kwargs):
         """
diff --git a/pandas/tests/series/test_timeseries.py b/pandas/tests/series/test_timeseries.py
index b9cf845ea47d7..a6c30aad46595 100644
--- a/pandas/tests/series/test_timeseries.py
+++ b/pandas/tests/series/test_timeseries.py
@@ -129,6 +129,37 @@ def test_shift2(self):
         idx = DatetimeIndex(['2000-01-01', '2000-01-02', '2000-01-04'])
         pytest.raises(NullFrequencyError, idx.shift, 1)
 
+    def test_shift_fill_value(self):
+        ts = Series(np.random.randn(5),
+                    index=date_range('1/1/2000', periods=5, freq='H'))
+
+        # fill_value should have no effect on shift with freq
+        result = ts.shift(1, freq='5T', fill_value=0)
+        exp_index = ts.index.shift(1, freq='5T')
+        tm.assert_index_equal(result.index, exp_index)
+        tm.assert_equal(result.iloc[0].value, ts.iloc[0].value)
+
+        # check that fill value works
+        result = ts.shift(1, fill_value=0.0)
+        tm.assert_equal(result.iloc[0].value, 0.0)
+        tm.assert_equal(result.iloc[1].value, ts.iloc[0].value)
+
+        result = ts.shift(2, fill_value=0.0)
+        tm.assert_equal(result.iloc[0].value, 0.0)
+        tm.assert_equal(result.iloc[1].value, 0.0)
+        tm.assert_equal(result.iloc[2].value, ts.iloc[0].value)
+
+        df = DataFrame(np.random.randn(5), index=date_range('1/1/2000', periods=5, freq='H'))
+
+        result = df.shift(1, fill_value=0.0)
+        tm.assert_equal(result.iloc[0, 0].value, 0.0)
+        tm.assert_equal(result.iloc[1, 0].value, df.iloc[0, 0].value)
+
+        result = df.shift(2, fill_value=0.0)
+        tm.assert_equal(result.iloc[0, 0].value, 0.0)
+        tm.assert_equal(result.iloc[1, 0].value, 0.0)
+        tm.assert_equal(result.iloc[2, 0].value, df.iloc[0, 0].value)
+
     def test_shift_dst(self):
         # GH 13926
         dates = date_range('2016-11-06', freq='H', periods=10, tz='US/Eastern')

From 6b4789d3386bfb7399729389dd407b3d9ef14093 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Thu, 6 Dec 2018 13:37:31 +0200
Subject: [PATCH 002/108] !U remove the data frame part form the time series

---
 pandas/tests/series/test_timeseries.py | 10 ----------
 1 file changed, 10 deletions(-)

diff --git a/pandas/tests/series/test_timeseries.py b/pandas/tests/series/test_timeseries.py
index a6c30aad46595..08790c806c3b1 100644
--- a/pandas/tests/series/test_timeseries.py
+++ b/pandas/tests/series/test_timeseries.py
@@ -149,16 +149,6 @@ def test_shift_fill_value(self):
         tm.assert_equal(result.iloc[1].value, 0.0)
         tm.assert_equal(result.iloc[2].value, ts.iloc[0].value)
 
-        df = DataFrame(np.random.randn(5), index=date_range('1/1/2000', periods=5, freq='H'))
-
-        result = df.shift(1, fill_value=0.0)
-        tm.assert_equal(result.iloc[0, 0].value, 0.0)
-        tm.assert_equal(result.iloc[1, 0].value, df.iloc[0, 0].value)
-
-        result = df.shift(2, fill_value=0.0)
-        tm.assert_equal(result.iloc[0, 0].value, 0.0)
-        tm.assert_equal(result.iloc[1, 0].value, 0.0)
-        tm.assert_equal(result.iloc[2, 0].value, df.iloc[0, 0].value)
 
     def test_shift_dst(self):
         # GH 13926

From 57c087e59056828ca1671355fddf4fbbe100f5da Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Thu, 6 Dec 2018 13:37:37 +0200
Subject: [PATCH 003/108] !U remove the data frame part form the time series

---
 pandas/tests/series/test_timeseries.py | 1 -
 1 file changed, 1 deletion(-)

diff --git a/pandas/tests/series/test_timeseries.py b/pandas/tests/series/test_timeseries.py
index 08790c806c3b1..68880adb08e14 100644
--- a/pandas/tests/series/test_timeseries.py
+++ b/pandas/tests/series/test_timeseries.py
@@ -149,7 +149,6 @@ def test_shift_fill_value(self):
         tm.assert_equal(result.iloc[1].value, 0.0)
         tm.assert_equal(result.iloc[2].value, ts.iloc[0].value)
 
-
     def test_shift_dst(self):
         # GH 13926
         dates = date_range('2016-11-06', freq='H', periods=10, tz='US/Eastern')

From 1852ea66dc44c4498645207f4d442b5b9e3c9031 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Thu, 6 Dec 2018 13:37:51 +0200
Subject: [PATCH 004/108] !U fix formatting

---
 pandas/core/generic.py | 3 ++-
 pandas/core/series.py  | 3 ++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/pandas/core/generic.py b/pandas/core/generic.py
index 3eafc137c527f..7f391d8040afe 100644
--- a/pandas/core/generic.py
+++ b/pandas/core/generic.py
@@ -8874,7 +8874,8 @@ def shift(self, periods=1, freq=None, axis=0, fill_value=np.nan):
 
         block_axis = self._get_block_manager_axis(axis)
         if freq is None:
-            new_data = self._data.shift(periods=periods, axis=block_axis, fill_value=fill_value)
+            new_data = self._data.shift(periods=periods, axis=block_axis,
+                                        fill_value=fill_value)
         else:
             return self.tshift(periods, freq, fill_value=fill_value)
 
diff --git a/pandas/core/series.py b/pandas/core/series.py
index 197c2f304700a..2ec67afd65078 100644
--- a/pandas/core/series.py
+++ b/pandas/core/series.py
@@ -3715,7 +3715,8 @@ def replace(self, to_replace=None, value=None, inplace=False, limit=None,
 
     @Appender(generic._shared_docs['shift'] % _shared_doc_kwargs)
     def shift(self, periods=1, freq=None, axis=0, fill_value=np.nan):
-        return super(Series, self).shift(periods=periods, freq=freq, axis=axis, fill_value=fill_value)
+        return super(Series, self).shift(periods=periods, freq=freq, axis=axis,
+                                         fill_value=fill_value)
 
     def reindex_axis(self, labels, axis=0, **kwargs):
         """

From 34612719b635587494587f9ad142f1fb7857fbd6 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Thu, 6 Dec 2018 13:48:12 +0200
Subject: [PATCH 005/108] !U add test for data_frame

---
 pandas/tests/frame/test_timeseries.py | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/pandas/tests/frame/test_timeseries.py b/pandas/tests/frame/test_timeseries.py
index 52f0b30bf0f0c..f7b030e5c234f 100644
--- a/pandas/tests/frame/test_timeseries.py
+++ b/pandas/tests/frame/test_timeseries.py
@@ -320,6 +320,19 @@ def test_shift_categorical(self):
         xp = DataFrame({'one': s1.shift(1), 'two': s2.shift(1)})
         assert_frame_equal(rs, xp)
 
+    def test_shift_fill_value(self):
+        df = DataFrame(np.random.randnint(5), index=date_range('1/1/2000',
+                                                            periods=5,
+                                                            freq='H'))
+        result = df.shift(1, fill_value=0)
+        tm.assert_equal(result.iloc[0, 0].value, 0)
+        tm.assert_equal(result.iloc[1, 0].value, df.iloc[0, 0].value)
+
+        result = df.shift(2, fill_value=0)
+        tm.assert_equal(result.iloc[0, 0].value, 0)
+        tm.assert_equal(result.iloc[1, 0].value, 0)
+        tm.assert_equal(result.iloc[2, 0].value, df.iloc[0, 0].value)
+
     def test_shift_empty(self):
         # Regression test for #8019
         df = DataFrame({'foo': []})

From 8b5cedbf28c787f5db786eb23e30c3ec48b48577 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Thu, 6 Dec 2018 13:50:54 +0200
Subject: [PATCH 006/108] !U remove fill_value from tshift

---
 pandas/core/generic.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/pandas/core/generic.py b/pandas/core/generic.py
index 7f391d8040afe..0293f7a7afa57 100644
--- a/pandas/core/generic.py
+++ b/pandas/core/generic.py
@@ -8877,7 +8877,7 @@ def shift(self, periods=1, freq=None, axis=0, fill_value=np.nan):
             new_data = self._data.shift(periods=periods, axis=block_axis,
                                         fill_value=fill_value)
         else:
-            return self.tshift(periods, freq, fill_value=fill_value)
+            return self.tshift(periods, freq)
 
         return self._constructor(new_data).__finalize__(self)
 
@@ -8917,7 +8917,7 @@ def slice_shift(self, periods=1, axis=0):
 
         return new_obj.__finalize__(self)
 
-    def tshift(self, periods=1, freq=None, axis=0, fill_value=np.nan):
+    def tshift(self, periods=1, freq=None, axis=0):
         """
         Shift the time index, using the index's frequency if available.
 

From 27226fa148103b6fa5a27f974f14d7a1a616450c Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Thu, 6 Dec 2018 14:04:25 +0200
Subject: [PATCH 007/108] !U remove unrelevant change

---
 pandas/core/arrays/datetimelike.py | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/pandas/core/arrays/datetimelike.py b/pandas/core/arrays/datetimelike.py
index a77faabd131ae..45eec41e498d1 100644
--- a/pandas/core/arrays/datetimelike.py
+++ b/pandas/core/arrays/datetimelike.py
@@ -780,7 +780,7 @@ def _addsub_offset_array(self, other, op):
         return self._from_sequence(res_values)
 
     @deprecate_kwarg(old_arg_name='n', new_arg_name='periods')
-    def shift(self, periods, freq=None, fill_value=np.nan):
+    def shift(self, periods, freq=None):
         """
         Shift index by desired number of time frequency increments.
 
@@ -810,9 +810,9 @@ def shift(self, periods, freq=None, fill_value=np.nan):
         Index.shift : Shift values of Index.
         PeriodIndex.shift : Shift values of PeriodIndex.
         """
-        return self._time_shift(periods=periods, freq=freq, fill_value=np.nan)
+        return self._time_shift(periods=periods, freq=freq)
 
-    def _time_shift(self, periods, freq=None, fill_value=np.nan):
+    def _time_shift(self, periods, freq=None):
         """
         Shift each value by `periods`.
 

From 29b8a6effd5d3efe06725bf09b649485a27614d4 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Thu, 6 Dec 2018 14:32:51 +0200
Subject: [PATCH 008/108] !U add doc for new fill_value argument for shift
 method

---
 pandas/core/generic.py | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/pandas/core/generic.py b/pandas/core/generic.py
index 0293f7a7afa57..7d85d368538bc 100644
--- a/pandas/core/generic.py
+++ b/pandas/core/generic.py
@@ -8829,7 +8829,10 @@ def mask(self, cond, other=np.nan, inplace=False, axis=None, level=None,
             data is not realigned. That is, use `freq` if you would like to
             extend the index when shifting and preserve the original data.
         axis : {0 or 'index', 1 or 'columns', None}, default None
-            Shift direction.
+            Shift direction.        
+        fill_value : None or value, default None (NaN).
+            Filling the empty space after shift with value provided by 
+            the user instead of NaN
 
         Returns
         -------
@@ -8865,6 +8868,14 @@ def mask(self, cond, other=np.nan, inplace=False, axis=None, level=None,
         2   NaN  15.0  18.0
         3   NaN  30.0  33.0
         4   NaN  45.0  48.0
+        
+        >>> df.shift(periods=3, fill_value=0.0)
+           Col1  Col2  Col3
+        0   0.0   0.0   0.0
+        1   0.0   0.0   0.0
+        2   0.0   0.0   0.0
+        3  10.0  13.0  17.0
+        4  20.0  23.0  27.0
     """)
 
     @Appender(_shared_docs['shift'] % _shared_doc_kwargs)

From cf6b2dd9b7e716747dd2a6159a68e09295a28abe Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Thu, 6 Dec 2018 14:35:04 +0200
Subject: [PATCH 009/108] !U add GH number

---
 pandas/tests/frame/test_timeseries.py  | 1 +
 pandas/tests/series/test_timeseries.py | 1 +
 2 files changed, 2 insertions(+)

diff --git a/pandas/tests/frame/test_timeseries.py b/pandas/tests/frame/test_timeseries.py
index f7b030e5c234f..d9368de3de1de 100644
--- a/pandas/tests/frame/test_timeseries.py
+++ b/pandas/tests/frame/test_timeseries.py
@@ -321,6 +321,7 @@ def test_shift_categorical(self):
         assert_frame_equal(rs, xp)
 
     def test_shift_fill_value(self):
+        # GH #24128
         df = DataFrame(np.random.randnint(5), index=date_range('1/1/2000',
                                                             periods=5,
                                                             freq='H'))
diff --git a/pandas/tests/series/test_timeseries.py b/pandas/tests/series/test_timeseries.py
index 68880adb08e14..700cc9d0af44c 100644
--- a/pandas/tests/series/test_timeseries.py
+++ b/pandas/tests/series/test_timeseries.py
@@ -130,6 +130,7 @@ def test_shift2(self):
         pytest.raises(NullFrequencyError, idx.shift, 1)
 
     def test_shift_fill_value(self):
+        # GH #24128
         ts = Series(np.random.randn(5),
                     index=date_range('1/1/2000', periods=5, freq='H'))
 

From 9f9962c1793569fd5f9620149277a6d5358ee223 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Thu, 6 Dec 2018 14:43:17 +0200
Subject: [PATCH 010/108] !U add versionated tag

---
 pandas/core/generic.py | 27 ++++++++++++++++-----------
 1 file changed, 16 insertions(+), 11 deletions(-)

diff --git a/pandas/core/generic.py b/pandas/core/generic.py
index 7d85d368538bc..415fdb643edae 100644
--- a/pandas/core/generic.py
+++ b/pandas/core/generic.py
@@ -8829,10 +8829,13 @@ def mask(self, cond, other=np.nan, inplace=False, axis=None, level=None,
             data is not realigned. That is, use `freq` if you would like to
             extend the index when shifting and preserve the original data.
         axis : {0 or 'index', 1 or 'columns', None}, default None
-            Shift direction.        
-        fill_value : None or value, default None (NaN).
-            Filling the empty space after shift with value provided by 
-            the user instead of NaN
+            Shift direction.
+            
+        .. versionchanged:: 0.24.0
+                
+            fill_value : None or value, default None (NaN).
+                Filling the empty space after shift with value provided by 
+                the user instead of NaN
 
         Returns
         -------
@@ -8869,13 +8872,15 @@ def mask(self, cond, other=np.nan, inplace=False, axis=None, level=None,
         3   NaN  30.0  33.0
         4   NaN  45.0  48.0
         
-        >>> df.shift(periods=3, fill_value=0.0)
-           Col1  Col2  Col3
-        0   0.0   0.0   0.0
-        1   0.0   0.0   0.0
-        2   0.0   0.0   0.0
-        3  10.0  13.0  17.0
-        4  20.0  23.0  27.0
+        .. versionchanged:: 0.24.0
+                
+            >>> df.shift(periods=3, fill_value=0.0)
+               Col1  Col2  Col3
+            0   0.0   0.0   0.0
+            1   0.0   0.0   0.0
+            2   0.0   0.0   0.0
+            3  10.0  13.0  17.0
+            4  20.0  23.0  27.0
     """)
 
     @Appender(_shared_docs['shift'] % _shared_doc_kwargs)

From 4c7b7629a03bdf98421c5bdad81c4e73309402af Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Thu, 6 Dec 2018 15:20:37 +0200
Subject: [PATCH 011/108] !U add fill_value to the group by interface

---
 pandas/core/groupby/groupby.py | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/pandas/core/groupby/groupby.py b/pandas/core/groupby/groupby.py
index 253860d83f49e..0255de90d7961 100644
--- a/pandas/core/groupby/groupby.py
+++ b/pandas/core/groupby/groupby.py
@@ -1993,7 +1993,7 @@ def _get_cythonized_result(self, how, grouper, aggregate=False,
 
     @Substitution(name='groupby')
     @Appender(_doc_template)
-    def shift(self, periods=1, freq=None, axis=0):
+    def shift(self, periods=1, freq=None, axis=0, fill_value=np.nan):
         """
         Shift each group by periods observations.
 
@@ -2003,10 +2003,11 @@ def shift(self, periods=1, freq=None, axis=0):
             number of periods to shift
         freq : frequency string
         axis : axis to shift, default 0
+        fill_value : None or value, default None (NaN).
         """
 
         if freq is not None or axis != 0:
-            return self.apply(lambda x: x.shift(periods, freq, axis))
+            return self.apply(lambda x: x.shift(periods, freq, axis, fill_value))
 
         return self._get_cythonized_result('group_shift_indexer',
                                            self.grouper, cython_dtype=np.int64,

From b36ca432ff999df2931006cb6eafe147e40c713b Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Thu, 6 Dec 2018 15:31:48 +0200
Subject: [PATCH 012/108] !U replace np.nan to None

---
 pandas/core/generic.py          | 2 +-
 pandas/core/groupby/groupby.py  | 2 +-
 pandas/core/internals/blocks.py | 2 +-
 pandas/core/series.py           | 2 +-
 4 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/pandas/core/generic.py b/pandas/core/generic.py
index 415fdb643edae..35282f9e08b4f 100644
--- a/pandas/core/generic.py
+++ b/pandas/core/generic.py
@@ -8884,7 +8884,7 @@ def mask(self, cond, other=np.nan, inplace=False, axis=None, level=None,
     """)
 
     @Appender(_shared_docs['shift'] % _shared_doc_kwargs)
-    def shift(self, periods=1, freq=None, axis=0, fill_value=np.nan):
+    def shift(self, periods=1, freq=None, axis=0, fill_value=None):
         if periods == 0:
             return self.copy()
 
diff --git a/pandas/core/groupby/groupby.py b/pandas/core/groupby/groupby.py
index 0255de90d7961..041d4a787f19d 100644
--- a/pandas/core/groupby/groupby.py
+++ b/pandas/core/groupby/groupby.py
@@ -1993,7 +1993,7 @@ def _get_cythonized_result(self, how, grouper, aggregate=False,
 
     @Substitution(name='groupby')
     @Appender(_doc_template)
-    def shift(self, periods=1, freq=None, axis=0, fill_value=np.nan):
+    def shift(self, periods=1, freq=None, axis=0, fill_value=None):
         """
         Shift each group by periods observations.
 
diff --git a/pandas/core/internals/blocks.py b/pandas/core/internals/blocks.py
index e2c2c884c7987..eca98ac2edb53 100644
--- a/pandas/core/internals/blocks.py
+++ b/pandas/core/internals/blocks.py
@@ -1260,7 +1260,7 @@ def diff(self, n, axis=1):
         new_values = algos.diff(self.values, n, axis=axis)
         return [self.make_block(values=new_values)]
 
-    def shift(self, periods, axis=0, fill_value=np.nan):
+    def shift(self, periods, axis=0, fill_value=None):
         """ shift the block by periods, possibly upcast """
 
         # convert integer to float if necessary. need to do a lot more than
diff --git a/pandas/core/series.py b/pandas/core/series.py
index 2ec67afd65078..5c0e14787e7e0 100644
--- a/pandas/core/series.py
+++ b/pandas/core/series.py
@@ -3714,7 +3714,7 @@ def replace(self, to_replace=None, value=None, inplace=False, limit=None,
                                            regex=regex, method=method)
 
     @Appender(generic._shared_docs['shift'] % _shared_doc_kwargs)
-    def shift(self, periods=1, freq=None, axis=0, fill_value=np.nan):
+    def shift(self, periods=1, freq=None, axis=0, fill_value=None):
         return super(Series, self).shift(periods=periods, freq=freq, axis=axis,
                                          fill_value=fill_value)
 

From a36e7c70b542a86ed3cba94fbadd3f2b19b8241b Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Thu, 6 Dec 2018 15:33:04 +0200
Subject: [PATCH 013/108] !U replace np.nan to None

---
 pandas/core/frame.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pandas/core/frame.py b/pandas/core/frame.py
index a6bc6226bda89..0834319c66644 100644
--- a/pandas/core/frame.py
+++ b/pandas/core/frame.py
@@ -3867,7 +3867,7 @@ def replace(self, to_replace=None, value=None, inplace=False, limit=None,
                                               method=method)
 
     @Appender(_shared_docs['shift'] % _shared_doc_kwargs)
-    def shift(self, periods=1, freq=None, axis=0, fill_value=np.nan):
+    def shift(self, periods=1, freq=None, axis=0, fill_value=None):
         return super(DataFrame, self).shift(periods=periods, freq=freq,
                                             axis=axis, fill_value=fill_value)
 

From 4c2ec2c075cc3f836d47fc2b325c2cd79bf21125 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Fri, 7 Dec 2018 02:39:50 +0200
Subject: [PATCH 014/108] !U add fill_value to the locations where it was
 missing

---
 pandas/core/arrays/base.py        |  9 +++++++--
 pandas/core/arrays/categorical.py |  8 +++++---
 pandas/core/arrays/period.py      |  4 ++--
 pandas/core/arrays/sparse.py      |  6 ++++--
 pandas/core/internals/blocks.py   | 12 +++++++-----
 5 files changed, 25 insertions(+), 14 deletions(-)

diff --git a/pandas/core/arrays/base.py b/pandas/core/arrays/base.py
index 9c6aa4a12923f..028f7a0e87d49 100644
--- a/pandas/core/arrays/base.py
+++ b/pandas/core/arrays/base.py
@@ -445,7 +445,7 @@ def dropna(self):
 
         return self[~self.isna()]
 
-    def shift(self, periods=1):
+    def shift(self, periods=1, fill_value=None):
         # type: (int) -> ExtensionArray
         """
         Shift values by desired number.
@@ -461,6 +461,8 @@ def shift(self, periods=1):
             The number of periods to shift. Negative values are allowed
             for shifting backwards.
 
+        .. versionadded:: 0.24.0
+            fill_value : None or value, default None (NaN)
         Returns
         -------
         shifted : ExtensionArray
@@ -469,7 +471,10 @@ def shift(self, periods=1):
         # stored in an instance of your ExtensionArray with `self.dtype`.
         if periods == 0:
             return self.copy()
-        empty = self._from_sequence([self.dtype.na_value] * abs(periods),
+        if fill_value is None:
+            fill_value = self.dtype.na_value
+
+        empty = self._from_sequence([fill_value] * abs(periods),
                                     dtype=self.dtype)
         if periods > 0:
             a = empty
diff --git a/pandas/core/arrays/categorical.py b/pandas/core/arrays/categorical.py
index 938ca53b5fdce..478cdf23f474f 100644
--- a/pandas/core/arrays/categorical.py
+++ b/pandas/core/arrays/categorical.py
@@ -1255,7 +1255,7 @@ def shape(self):
 
         return tuple([len(self._codes)])
 
-    def shift(self, periods):
+    def shift(self, periods, fill_value=None):
         """
         Shift Categorical by desired number of periods.
 
@@ -1275,10 +1275,12 @@ def shift(self, periods):
             raise NotImplementedError("Categorical with ndim > 1.")
         if np.prod(codes.shape) and (periods != 0):
             codes = np.roll(codes, ensure_platform_int(periods), axis=0)
+            if fill_value is None:
+                fill_value = -1
             if periods > 0:
-                codes[:periods] = -1
+                codes[:periods] = fill_value
             else:
-                codes[periods:] = -1
+                codes[periods:] = fill_value
 
         return self.from_codes(codes, categories=self.categories,
                                ordered=self.ordered)
diff --git a/pandas/core/arrays/period.py b/pandas/core/arrays/period.py
index d9dde1c699761..43372fd2e9fb0 100644
--- a/pandas/core/arrays/period.py
+++ b/pandas/core/arrays/period.py
@@ -457,7 +457,7 @@ def value_counts(self, dropna=False):
 
     # --------------------------------------------------------------------
 
-    def shift(self, periods=1):
+    def shift(self, periods=1, fill_value=None):
         """
         Shift values by desired number.
 
@@ -479,7 +479,7 @@ def shift(self, periods=1):
         # TODO(DatetimeArray): remove
         # The semantics for Index.shift differ from EA.shift
         # then just call super.
-        return ExtensionArray.shift(self, periods)
+        return ExtensionArray.shift(self, periods, fill_value=fill_value)
 
     def _time_shift(self, n, freq=None):
         """
diff --git a/pandas/core/arrays/sparse.py b/pandas/core/arrays/sparse.py
index 134466d769ada..92c3aaa4a418f 100644
--- a/pandas/core/arrays/sparse.py
+++ b/pandas/core/arrays/sparse.py
@@ -887,7 +887,7 @@ def fillna(self, value=None, method=None, limit=None):
 
         return self._simple_new(new_values, self._sparse_index, new_dtype)
 
-    def shift(self, periods=1):
+    def shift(self, periods=1, fill_value=None):
 
         if periods == 0:
             return self.copy()
@@ -900,7 +900,9 @@ def shift(self, periods=1):
         else:
             arr = self
 
-        empty = self._from_sequence([self.dtype.na_value] * abs(periods),
+        if fill_value is None:
+            fill_value = self.dtype.na_value
+        empty = self._from_sequence([fill_value] * abs(periods),
                                     dtype=arr.dtype)
         if periods > 0:
             a = empty
diff --git a/pandas/core/internals/blocks.py b/pandas/core/internals/blocks.py
index eca98ac2edb53..0bef787a357a7 100644
--- a/pandas/core/internals/blocks.py
+++ b/pandas/core/internals/blocks.py
@@ -1955,7 +1955,7 @@ def interpolate(self, method='pad', axis=0, inplace=False, limit=None,
                                  limit=limit),
             placement=self.mgr_locs)
 
-    def shift(self, periods, axis=0):
+    def shift(self, periods, axis=0, fill_value=None):
         """
         Shift the block by `periods`.
 
@@ -1963,7 +1963,7 @@ def shift(self, periods, axis=0):
         ExtensionBlock.
         """
         # type: (int, Optional[BlockPlacement]) -> List[ExtensionBlock]
-        return [self.make_block_same_class(self.values.shift(periods=periods),
+        return [self.make_block_same_class(self.values.shift(periods=periods, fill_value=fill_value),
                                            placement=self.mgr_locs,
                                            ndim=self.ndim)]
 
@@ -2933,7 +2933,7 @@ def _try_coerce_result(self, result):
     def _box_func(self):
         return lambda x: tslibs.Timestamp(x, tz=self.dtype.tz)
 
-    def shift(self, periods, axis=0):
+    def shift(self, periods, axis=0, fill_value=None):
         """ shift the block by periods """
 
         # think about moving this to the DatetimeIndex. This is a non-freq
@@ -2948,10 +2948,12 @@ def shift(self, periods, axis=0):
 
         new_values = self.values.asi8.take(indexer)
 
+        if fill_value is None:
+            fill_value = tslibs.iNaT
         if periods > 0:
-            new_values[:periods] = tslibs.iNaT
+            new_values[:periods] = fill_value
         else:
-            new_values[periods:] = tslibs.iNaT
+            new_values[periods:] = fill_value
 
         new_values = self.values._shallow_copy(new_values)
         return [self.make_block_same_class(new_values,

From fbf3d737a9b8c3e060c3e4168486127274cad0ce Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Fri, 7 Dec 2018 03:55:28 +0200
Subject: [PATCH 015/108] !U fix series test

---
 pandas/tests/series/test_timeseries.py | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/pandas/tests/series/test_timeseries.py b/pandas/tests/series/test_timeseries.py
index 700cc9d0af44c..a6de02f8aafac 100644
--- a/pandas/tests/series/test_timeseries.py
+++ b/pandas/tests/series/test_timeseries.py
@@ -138,17 +138,17 @@ def test_shift_fill_value(self):
         result = ts.shift(1, freq='5T', fill_value=0)
         exp_index = ts.index.shift(1, freq='5T')
         tm.assert_index_equal(result.index, exp_index)
-        tm.assert_equal(result.iloc[0].value, ts.iloc[0].value)
+        tm.assert_equal(result.iloc[0], ts.iloc[0])
 
         # check that fill value works
         result = ts.shift(1, fill_value=0.0)
-        tm.assert_equal(result.iloc[0].value, 0.0)
-        tm.assert_equal(result.iloc[1].value, ts.iloc[0].value)
+        tm.assert_equal(result.iloc[0], 0.0)
+        tm.assert_equal(result.iloc[1], ts.iloc[0])
 
         result = ts.shift(2, fill_value=0.0)
-        tm.assert_equal(result.iloc[0].value, 0.0)
-        tm.assert_equal(result.iloc[1].value, 0.0)
-        tm.assert_equal(result.iloc[2].value, ts.iloc[0].value)
+        tm.assert_equal(result.iloc[0], 0.0)
+        tm.assert_equal(result.iloc[1], 0.0)
+        tm.assert_equal(result.iloc[2], ts.iloc[0])
 
     def test_shift_dst(self):
         # GH 13926

From bb722a60192aeb67d9829496668eea3bc92c4ac4 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Fri, 7 Dec 2018 03:56:27 +0200
Subject: [PATCH 016/108] !U fix method name and values comparison for the new
 test

---
 pandas/tests/frame/test_timeseries.py | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/pandas/tests/frame/test_timeseries.py b/pandas/tests/frame/test_timeseries.py
index d9368de3de1de..ef13e1884cb11 100644
--- a/pandas/tests/frame/test_timeseries.py
+++ b/pandas/tests/frame/test_timeseries.py
@@ -322,17 +322,17 @@ def test_shift_categorical(self):
 
     def test_shift_fill_value(self):
         # GH #24128
-        df = DataFrame(np.random.randnint(5), index=date_range('1/1/2000',
+        df = DataFrame(np.random.randint(5), index=date_range('1/1/2000',
                                                             periods=5,
                                                             freq='H'))
         result = df.shift(1, fill_value=0)
-        tm.assert_equal(result.iloc[0, 0].value, 0)
-        tm.assert_equal(result.iloc[1, 0].value, df.iloc[0, 0].value)
+        tm.assert_equal(result.iloc[0, 0], 0)
+        tm.assert_equal(result.iloc[1, 0], df.iloc[0, 0])
 
         result = df.shift(2, fill_value=0)
-        tm.assert_equal(result.iloc[0, 0].value, 0)
-        tm.assert_equal(result.iloc[1, 0].value, 0)
-        tm.assert_equal(result.iloc[2, 0].value, df.iloc[0, 0].value)
+        tm.assert_equal(result.iloc[0, 0], 0)
+        tm.assert_equal(result.iloc[1, 0], 0)
+        tm.assert_equal(result.iloc[2, 0], df.iloc[0, 0])
 
     def test_shift_empty(self):
         # Regression test for #8019

From 1b1fdc2031504b7ee64669257ad744db3f7fccba Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Fri, 7 Dec 2018 19:40:44 +0200
Subject: [PATCH 017/108] !U fix dataframe constructor

---
 pandas/tests/frame/test_timeseries.py | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/pandas/tests/frame/test_timeseries.py b/pandas/tests/frame/test_timeseries.py
index ef13e1884cb11..4fc8dd5f4a862 100644
--- a/pandas/tests/frame/test_timeseries.py
+++ b/pandas/tests/frame/test_timeseries.py
@@ -322,9 +322,8 @@ def test_shift_categorical(self):
 
     def test_shift_fill_value(self):
         # GH #24128
-        df = DataFrame(np.random.randint(5), index=date_range('1/1/2000',
-                                                            periods=5,
-                                                            freq='H'))
+        df = DataFrame(np.random.randint(5, size=5),
+                       index=date_range('1/1/2000', periods=5, freq='H'))
         result = df.shift(1, fill_value=0)
         tm.assert_equal(result.iloc[0, 0], 0)
         tm.assert_equal(result.iloc[1, 0], df.iloc[0, 0])

From c3f462ceca874d5304db56ec2e93eeafe8dfcc7f Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Sat, 8 Dec 2018 00:00:56 +0200
Subject: [PATCH 018/108] !U change the assert method used for new tests

---
 pandas/tests/frame/test_timeseries.py  | 10 +++++-----
 pandas/tests/series/test_timeseries.py | 12 ++++++------
 2 files changed, 11 insertions(+), 11 deletions(-)

diff --git a/pandas/tests/frame/test_timeseries.py b/pandas/tests/frame/test_timeseries.py
index 4fc8dd5f4a862..1fb3c0d402a26 100644
--- a/pandas/tests/frame/test_timeseries.py
+++ b/pandas/tests/frame/test_timeseries.py
@@ -325,13 +325,13 @@ def test_shift_fill_value(self):
         df = DataFrame(np.random.randint(5, size=5),
                        index=date_range('1/1/2000', periods=5, freq='H'))
         result = df.shift(1, fill_value=0)
-        tm.assert_equal(result.iloc[0, 0], 0)
-        tm.assert_equal(result.iloc[1, 0], df.iloc[0, 0])
+        np.testing.assert_equal(result.iloc[0, 0], 0)
+        np.testing.assert_equal(result.iloc[1, 0], df.iloc[0, 0])
 
         result = df.shift(2, fill_value=0)
-        tm.assert_equal(result.iloc[0, 0], 0)
-        tm.assert_equal(result.iloc[1, 0], 0)
-        tm.assert_equal(result.iloc[2, 0], df.iloc[0, 0])
+        np.testing.assert_equal(result.iloc[0, 0], 0)
+        np.testing.assert_equal(result.iloc[1, 0], 0)
+        np.testing.assert_equal(result.iloc[2, 0], df.iloc[0, 0])
 
     def test_shift_empty(self):
         # Regression test for #8019
diff --git a/pandas/tests/series/test_timeseries.py b/pandas/tests/series/test_timeseries.py
index a6de02f8aafac..fc1ab66c47ed2 100644
--- a/pandas/tests/series/test_timeseries.py
+++ b/pandas/tests/series/test_timeseries.py
@@ -138,17 +138,17 @@ def test_shift_fill_value(self):
         result = ts.shift(1, freq='5T', fill_value=0)
         exp_index = ts.index.shift(1, freq='5T')
         tm.assert_index_equal(result.index, exp_index)
-        tm.assert_equal(result.iloc[0], ts.iloc[0])
+        np.testing.assert_equal(result.iloc[0], ts.iloc[0])
 
         # check that fill value works
         result = ts.shift(1, fill_value=0.0)
-        tm.assert_equal(result.iloc[0], 0.0)
-        tm.assert_equal(result.iloc[1], ts.iloc[0])
+        np.testing.assert_equal(result.iloc[0], 0.0)
+        np.testing.assert_equal(result.iloc[1], ts.iloc[0])
 
         result = ts.shift(2, fill_value=0.0)
-        tm.assert_equal(result.iloc[0], 0.0)
-        tm.assert_equal(result.iloc[1], 0.0)
-        tm.assert_equal(result.iloc[2], ts.iloc[0])
+        np.testing.assert_equal(result.iloc[0], 0.0)
+        np.testing.assert_equal(result.iloc[1], 0.0)
+        np.testing.assert_equal(result.iloc[2], ts.iloc[0])
 
     def test_shift_dst(self):
         # GH 13926

From e44b514c8edafb7e6aa186132e5da0adaefcd5ea Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Sat, 8 Dec 2018 13:09:15 +0200
Subject: [PATCH 019/108] !U change formatting and doc scripts

---
 pandas/core/arrays/base.py        |  5 +++--
 pandas/core/arrays/categorical.py |  2 ++
 pandas/core/arrays/period.py      |  2 ++
 pandas/core/generic.py            | 27 +++++++++++++--------------
 pandas/core/internals/blocks.py   |  8 +++++---
 5 files changed, 25 insertions(+), 19 deletions(-)

diff --git a/pandas/core/arrays/base.py b/pandas/core/arrays/base.py
index 028f7a0e87d49..df910dd754e8c 100644
--- a/pandas/core/arrays/base.py
+++ b/pandas/core/arrays/base.py
@@ -461,8 +461,9 @@ def shift(self, periods=1, fill_value=None):
             The number of periods to shift. Negative values are allowed
             for shifting backwards.
 
-        .. versionadded:: 0.24.0
-            fill_value : None or value, default None (NaN)
+        fill_value : None or value, default None (NaN)
+            .. versionadded:: 0.24.0
+
         Returns
         -------
         shifted : ExtensionArray
diff --git a/pandas/core/arrays/categorical.py b/pandas/core/arrays/categorical.py
index 478cdf23f474f..bae753b8e94ed 100644
--- a/pandas/core/arrays/categorical.py
+++ b/pandas/core/arrays/categorical.py
@@ -1263,6 +1263,8 @@ def shift(self, periods, fill_value=None):
         ----------
         periods : int
             Number of periods to move, can be positive or negative
+        fill_value : None or value, default None (NaN)
+            .. versionadded:: 0.24.0
 
         Returns
         -------
diff --git a/pandas/core/arrays/period.py b/pandas/core/arrays/period.py
index 43372fd2e9fb0..5a819d11080db 100644
--- a/pandas/core/arrays/period.py
+++ b/pandas/core/arrays/period.py
@@ -471,6 +471,8 @@ def shift(self, periods=1, fill_value=None):
         periods : int, default 1
             The number of periods to shift. Negative values are allowed
             for shifting backwards.
+        fill_value : None or value, default None (NaT)
+            .. versionadded:: 0.24.0
 
         Returns
         -------
diff --git a/pandas/core/generic.py b/pandas/core/generic.py
index 35282f9e08b4f..6b9f08347da34 100644
--- a/pandas/core/generic.py
+++ b/pandas/core/generic.py
@@ -8830,12 +8830,12 @@ def mask(self, cond, other=np.nan, inplace=False, axis=None, level=None,
             extend the index when shifting and preserve the original data.
         axis : {0 or 'index', 1 or 'columns', None}, default None
             Shift direction.
+        fill_value : object, optional
+            the scalar value to use for newly introduced missing values.
+            the default depends on the dtype of `self`. for numeric data,
+            ``np.nan`` is used. for datelike, ``pandas.nat`` is used.    
             
-        .. versionchanged:: 0.24.0
-                
-            fill_value : None or value, default None (NaN).
-                Filling the empty space after shift with value provided by 
-                the user instead of NaN
+            .. versionchanged:: 0.24.0
 
         Returns
         -------
@@ -8872,15 +8872,14 @@ def mask(self, cond, other=np.nan, inplace=False, axis=None, level=None,
         3   NaN  30.0  33.0
         4   NaN  45.0  48.0
         
-        .. versionchanged:: 0.24.0
-                
-            >>> df.shift(periods=3, fill_value=0.0)
-               Col1  Col2  Col3
-            0   0.0   0.0   0.0
-            1   0.0   0.0   0.0
-            2   0.0   0.0   0.0
-            3  10.0  13.0  17.0
-            4  20.0  23.0  27.0
+        >>> df.shift(periods=3, fill_value=0.0)
+           Col1  Col2  Col3
+        0   0.0   0.0   0.0
+        1   0.0   0.0   0.0
+        2   0.0   0.0   0.0
+        3  10.0  13.0  17.0
+        4  20.0  23.0  27.0
+
     """)
 
     @Appender(_shared_docs['shift'] % _shared_doc_kwargs)
diff --git a/pandas/core/internals/blocks.py b/pandas/core/internals/blocks.py
index 0bef787a357a7..3881aae9287d0 100644
--- a/pandas/core/internals/blocks.py
+++ b/pandas/core/internals/blocks.py
@@ -1963,9 +1963,11 @@ def shift(self, periods, axis=0, fill_value=None):
         ExtensionBlock.
         """
         # type: (int, Optional[BlockPlacement]) -> List[ExtensionBlock]
-        return [self.make_block_same_class(self.values.shift(periods=periods, fill_value=fill_value),
-                                           placement=self.mgr_locs,
-                                           ndim=self.ndim)]
+        return [
+            self.make_block_same_class(self.values.shift(periods=periods,
+                                                         fill_value=fill_value),
+                                       placement=self.mgr_locs, ndim=self.ndim)
+        ]
 
     @property
     def _ftype(self):

From 38f621caafd81c75fb2c9d6f03fab8efae067dc3 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Sat, 8 Dec 2018 13:15:27 +0200
Subject: [PATCH 020/108] !U add doc strings

---
 pandas/core/arrays/base.py        | 5 ++++-
 pandas/core/arrays/categorical.py | 5 ++++-
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/pandas/core/arrays/base.py b/pandas/core/arrays/base.py
index df910dd754e8c..b614f4521af27 100644
--- a/pandas/core/arrays/base.py
+++ b/pandas/core/arrays/base.py
@@ -461,7 +461,10 @@ def shift(self, periods=1, fill_value=None):
             The number of periods to shift. Negative values are allowed
             for shifting backwards.
 
-        fill_value : None or value, default None (NaN)
+        fill_value : object, optional
+            The scalar value to use for newly introduced missing values.
+            The default is ``self.dtype.na_value``.
+
             .. versionadded:: 0.24.0
 
         Returns
diff --git a/pandas/core/arrays/categorical.py b/pandas/core/arrays/categorical.py
index bae753b8e94ed..6d4846cf25698 100644
--- a/pandas/core/arrays/categorical.py
+++ b/pandas/core/arrays/categorical.py
@@ -1263,7 +1263,10 @@ def shift(self, periods, fill_value=None):
         ----------
         periods : int
             Number of periods to move, can be positive or negative
-        fill_value : None or value, default None (NaN)
+        fill_value : object, optional
+            The scalar value to use for newly introduced missing values.
+            The default is ``-1``.
+
             .. versionadded:: 0.24.0
 
         Returns

From d9d9fdb06bba706c9b544d8b867ecce57a149b16 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Sat, 8 Dec 2018 13:51:14 +0200
Subject: [PATCH 021/108] !U add check for fill_value present in the
 categorical categories

---
 pandas/core/arrays/categorical.py | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/pandas/core/arrays/categorical.py b/pandas/core/arrays/categorical.py
index 6d4846cf25698..25b6fb1c59204 100644
--- a/pandas/core/arrays/categorical.py
+++ b/pandas/core/arrays/categorical.py
@@ -1282,6 +1282,10 @@ def shift(self, periods, fill_value=None):
             codes = np.roll(codes, ensure_platform_int(periods), axis=0)
             if fill_value is None:
                 fill_value = -1
+            elif fill_value in self.categories:
+                fill_value = self.categories.get_loc(fill_value)
+            else:
+                raise ValueError("'fill_value={}' is not present in this Categorical's categories".format(fill_value))
             if periods > 0:
                 codes[:periods] = fill_value
             else:

From cc6f370fee500397e384e58ff6f804cadb7da871 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Sun, 9 Dec 2018 02:08:52 +0200
Subject: [PATCH 022/108] !U change test for frame

---
 pandas/tests/frame/test_timeseries.py | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/pandas/tests/frame/test_timeseries.py b/pandas/tests/frame/test_timeseries.py
index 1fb3c0d402a26..346b56c9a9d69 100644
--- a/pandas/tests/frame/test_timeseries.py
+++ b/pandas/tests/frame/test_timeseries.py
@@ -322,16 +322,17 @@ def test_shift_categorical(self):
 
     def test_shift_fill_value(self):
         # GH #24128
-        df = DataFrame(np.random.randint(5, size=5),
+        df = DataFrame([1, 2, 3, 4, 5],
+                       index=date_range('1/1/2000', periods=5, freq='H'))
+        expected = DataFrame([0, 1, 2, 3, 4],
                        index=date_range('1/1/2000', periods=5, freq='H'))
         result = df.shift(1, fill_value=0)
-        np.testing.assert_equal(result.iloc[0, 0], 0)
-        np.testing.assert_equal(result.iloc[1, 0], df.iloc[0, 0])
+        assert_frame_equal(result, expected)
 
+        expected = DataFrame([0, 0, 1, 2, 3],
+                       index=date_range('1/1/2000', periods=5, freq='H'))
         result = df.shift(2, fill_value=0)
-        np.testing.assert_equal(result.iloc[0, 0], 0)
-        np.testing.assert_equal(result.iloc[1, 0], 0)
-        np.testing.assert_equal(result.iloc[2, 0], df.iloc[0, 0])
+        assert_frame_equal(result, expected)
 
     def test_shift_empty(self):
         # Regression test for #8019

From 36194100428c0a28fe3d142f1b3fc65b71850d76 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Sun, 9 Dec 2018 02:14:21 +0200
Subject: [PATCH 023/108] !U change test for series shift with fill value to
 avoid formatting error

---
 pandas/tests/series/test_timeseries.py | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/pandas/tests/series/test_timeseries.py b/pandas/tests/series/test_timeseries.py
index fc1ab66c47ed2..f7bd5e7936a30 100644
--- a/pandas/tests/series/test_timeseries.py
+++ b/pandas/tests/series/test_timeseries.py
@@ -131,24 +131,25 @@ def test_shift2(self):
 
     def test_shift_fill_value(self):
         # GH #24128
-        ts = Series(np.random.randn(5),
+        ts = Series([1.0, 2.0, 3.0, 4.0, 5.0],
                     index=date_range('1/1/2000', periods=5, freq='H'))
 
         # fill_value should have no effect on shift with freq
         result = ts.shift(1, freq='5T', fill_value=0)
         exp_index = ts.index.shift(1, freq='5T')
         tm.assert_index_equal(result.index, exp_index)
-        np.testing.assert_equal(result.iloc[0], ts.iloc[0])
+        tm.assert_numpy_array_equal(result.values, ts.values)
 
+        expected = Series([0.0, 1.0, 2.0, 3.0, 4.0],
+                    index=date_range('1/1/2000', periods=5, freq='H'))
         # check that fill value works
         result = ts.shift(1, fill_value=0.0)
-        np.testing.assert_equal(result.iloc[0], 0.0)
-        np.testing.assert_equal(result.iloc[1], ts.iloc[0])
+        tm.assert_series_equal(result, expected)
 
+        expected = Series([0.0, 0.0, 1.0, 2.0, 3.0],
+                    index=date_range('1/1/2000', periods=5, freq='H'))
         result = ts.shift(2, fill_value=0.0)
-        np.testing.assert_equal(result.iloc[0], 0.0)
-        np.testing.assert_equal(result.iloc[1], 0.0)
-        np.testing.assert_equal(result.iloc[2], ts.iloc[0])
+        tm.assert_series_equal(result, expected)
 
     def test_shift_dst(self):
         # GH 13926

From ca5ba24b2adbd0e547c98cbadaed4b5283e63613 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Sun, 9 Dec 2018 03:23:20 +0200
Subject: [PATCH 024/108] !U remove dot

---
 pandas/core/groupby/groupby.py | 26 ++++++++++++--------------
 1 file changed, 12 insertions(+), 14 deletions(-)

diff --git a/pandas/core/groupby/groupby.py b/pandas/core/groupby/groupby.py
index 041d4a787f19d..327ab4a788b6d 100644
--- a/pandas/core/groupby/groupby.py
+++ b/pandas/core/groupby/groupby.py
@@ -8,38 +8,36 @@ class providing the base-class of operations.
 """
 
 import collections
-from contextlib import contextmanager
 import datetime
-from functools import partial, wraps
 import types
 import warnings
+from contextlib import contextmanager
+from functools import partial, wraps
 
 import numpy as np
 
-from pandas._libs import Timestamp, groupby as libgroupby
 import pandas.compat as compat
+import pandas.core.algorithms as algorithms
+import pandas.core.common as com
+from pandas._libs import Timestamp, groupby as libgroupby
 from pandas.compat import callable, range, set_function_name, zip
 from pandas.compat.numpy import function as nv
-from pandas.errors import AbstractMethodError
-from pandas.util._decorators import Appender, Substitution, cache_readonly
-from pandas.util._validators import validate_kwargs
-
+from pandas.core.base import (
+    DataError, GroupByError, PandasObject, SelectionMixin, SpecificationError)
+from pandas.core.config import option_context
 from pandas.core.dtypes.cast import maybe_downcast_to_dtype
 from pandas.core.dtypes.common import (
     ensure_float, is_extension_array_dtype, is_numeric_dtype, is_scalar)
 from pandas.core.dtypes.missing import isna, notna
-
-import pandas.core.algorithms as algorithms
-from pandas.core.base import (
-    DataError, GroupByError, PandasObject, SelectionMixin, SpecificationError)
-import pandas.core.common as com
-from pandas.core.config import option_context
 from pandas.core.frame import DataFrame
 from pandas.core.generic import NDFrame
 from pandas.core.groupby import base
 from pandas.core.index import Index, MultiIndex
 from pandas.core.series import Series
 from pandas.core.sorting import get_group_index_sorter
+from pandas.errors import AbstractMethodError
+from pandas.util._decorators import Appender, Substitution, cache_readonly
+from pandas.util._validators import validate_kwargs
 
 _doc_template = """
         See Also
@@ -2003,7 +2001,7 @@ def shift(self, periods=1, freq=None, axis=0, fill_value=None):
             number of periods to shift
         freq : frequency string
         axis : axis to shift, default 0
-        fill_value : None or value, default None (NaN).
+        fill_value : None or value, default None (NaN)
         """
 
         if freq is not None or axis != 0:

From c195a136b7079e284417dcfa7f263697f1fbbd61 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Sun, 9 Dec 2018 03:31:30 +0200
Subject: [PATCH 025/108] !U remove empty line

---
 pandas/core/generic.py | 26 +++++++++++---------------
 1 file changed, 11 insertions(+), 15 deletions(-)

diff --git a/pandas/core/generic.py b/pandas/core/generic.py
index 6b9f08347da34..c569a75347adf 100644
--- a/pandas/core/generic.py
+++ b/pandas/core/generic.py
@@ -9,17 +9,18 @@
 
 import numpy as np
 
-from pandas._libs import Timestamp, iNaT, properties
+import pandas as pd
 import pandas.compat as compat
+import pandas.core.algorithms as algos
+import pandas.core.common as com
+import pandas.core.indexing as indexing
+from pandas._libs import Timestamp, iNaT, properties
 from pandas.compat import (
     cPickle as pkl, isidentifier, lrange, lzip, map, set_function_name,
     string_types, to_str, zip)
 from pandas.compat.numpy import function as nv
-from pandas.errors import AbstractMethodError
-from pandas.util._decorators import (
-    Appender, Substitution, rewrite_axis_style_signature)
-from pandas.util._validators import validate_bool_kwarg, validate_fillna_kwargs
-
+from pandas.core import config, missing, nanops
+from pandas.core.base import PandasObject, SelectionMixin
 from pandas.core.dtypes.cast import maybe_promote, maybe_upcast_putmask
 from pandas.core.dtypes.common import (
     ensure_int64, ensure_object, is_bool, is_bool_dtype,
@@ -30,23 +31,19 @@
 from pandas.core.dtypes.generic import ABCDataFrame, ABCPanel, ABCSeries
 from pandas.core.dtypes.inference import is_hashable
 from pandas.core.dtypes.missing import isna, notna
-
-import pandas as pd
-from pandas.core import config, missing, nanops
-import pandas.core.algorithms as algos
-from pandas.core.base import PandasObject, SelectionMixin
-import pandas.core.common as com
 from pandas.core.index import (
     Index, InvalidIndexError, MultiIndex, RangeIndex, ensure_index)
 from pandas.core.indexes.datetimes import DatetimeIndex
 from pandas.core.indexes.period import Period, PeriodIndex
-import pandas.core.indexing as indexing
 from pandas.core.internals import BlockManager
 from pandas.core.ops import _align_method_FRAME
-
+from pandas.errors import AbstractMethodError
 from pandas.io.formats.format import DataFrameFormatter, format_percentiles
 from pandas.io.formats.printing import pprint_thing
 from pandas.tseries.frequencies import to_offset
+from pandas.util._decorators import (
+    Appender, Substitution, rewrite_axis_style_signature)
+from pandas.util._validators import validate_bool_kwarg, validate_fillna_kwargs
 
 # goal is to be able to define the docs close to function, while still being
 # able to share
@@ -8879,7 +8876,6 @@ def mask(self, cond, other=np.nan, inplace=False, axis=None, level=None,
         2   0.0   0.0   0.0
         3  10.0  13.0  17.0
         4  20.0  23.0  27.0
-
     """)
 
     @Appender(_shared_docs['shift'] % _shared_doc_kwargs)

From af90a0033ee4bc6780e96e292217d120e80b8be6 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Sun, 9 Dec 2018 03:33:07 +0200
Subject: [PATCH 026/108] !U fix the line lenght

---
 pandas/core/internals/blocks.py | 27 ++++++++++++---------------
 1 file changed, 12 insertions(+), 15 deletions(-)

diff --git a/pandas/core/internals/blocks.py b/pandas/core/internals/blocks.py
index 3881aae9287d0..4c9ac76c6ed4a 100644
--- a/pandas/core/internals/blocks.py
+++ b/pandas/core/internals/blocks.py
@@ -1,18 +1,22 @@
 # -*- coding: utf-8 -*-
-from datetime import date, datetime, timedelta
 import functools
 import inspect
 import re
 import warnings
+from datetime import date, datetime, timedelta
 
 import numpy as np
 
+import pandas.compat as compat
+import pandas.core.algorithms as algos
+import pandas.core.common as com
+import pandas.core.dtypes.concat as _concat
+import pandas.core.missing as missing
 from pandas._libs import internals as libinternals, lib, tslib, tslibs
 from pandas._libs.tslibs import Timedelta, conversion
-import pandas.compat as compat
 from pandas.compat import range, zip
-from pandas.util._validators import validate_bool_kwarg
-
+from pandas.core.arrays import Categorical, ExtensionArray
+from pandas.core.base import PandasObject
 from pandas.core.dtypes.cast import (
     astype_nansafe, find_common_type, infer_dtype_from,
     infer_dtype_from_scalar, maybe_convert_objects, maybe_downcast_to_dtype,
@@ -24,24 +28,17 @@
     is_float_dtype, is_integer, is_integer_dtype, is_list_like,
     is_numeric_v_string_like, is_object_dtype, is_re, is_re_compilable,
     is_sparse, is_timedelta64_dtype, pandas_dtype)
-import pandas.core.dtypes.concat as _concat
 from pandas.core.dtypes.dtypes import (
     CategoricalDtype, DatetimeTZDtype, ExtensionDtype, PandasExtensionDtype)
 from pandas.core.dtypes.generic import (
     ABCDatetimeIndex, ABCExtensionArray, ABCIndexClass, ABCSeries)
 from pandas.core.dtypes.missing import (
     _isna_compat, array_equivalent, is_null_datelike_scalar, isna, notna)
-
-import pandas.core.algorithms as algos
-from pandas.core.arrays import Categorical, ExtensionArray
-from pandas.core.base import PandasObject
-import pandas.core.common as com
 from pandas.core.indexes.datetimes import DatetimeIndex
 from pandas.core.indexes.timedeltas import TimedeltaIndex
 from pandas.core.indexing import check_setitem_lengths
-import pandas.core.missing as missing
-
 from pandas.io.formats.printing import pprint_thing
+from pandas.util._validators import validate_bool_kwarg
 
 
 class Block(PandasObject):
@@ -1964,9 +1961,9 @@ def shift(self, periods, axis=0, fill_value=None):
         """
         # type: (int, Optional[BlockPlacement]) -> List[ExtensionBlock]
         return [
-            self.make_block_same_class(self.values.shift(periods=periods,
-                                                         fill_value=fill_value),
-                                       placement=self.mgr_locs, ndim=self.ndim)
+            self.make_block_same_class(
+                self.values.shift(periods=periods, fill_value=fill_value),
+                placement=self.mgr_locs, ndim=self.ndim)
         ]
 
     @property

From 2f9b7126cd74414fb262703af8236a4cad878f19 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Sun, 9 Dec 2018 03:33:58 +0200
Subject: [PATCH 027/108] !U format the exception message

---
 pandas/core/arrays/categorical.py | 28 +++++++++++++---------------
 1 file changed, 13 insertions(+), 15 deletions(-)

diff --git a/pandas/core/arrays/categorical.py b/pandas/core/arrays/categorical.py
index 25b6fb1c59204..aa2ba5519435c 100644
--- a/pandas/core/arrays/categorical.py
+++ b/pandas/core/arrays/categorical.py
@@ -5,14 +5,16 @@
 
 import numpy as np
 
-from pandas._libs import algos as libalgos, lib
 import pandas.compat as compat
+import pandas.core.algorithms as algorithms
+import pandas.core.common as com
+from pandas._libs import algos as libalgos, lib
 from pandas.compat import lzip, u
 from pandas.compat.numpy import function as nv
-from pandas.util._decorators import (
-    Appender, Substitution, cache_readonly, deprecate_kwarg)
-from pandas.util._validators import validate_bool_kwarg, validate_fillna_kwargs
-
+from pandas.core.accessor import PandasDelegate, delegate_names
+from pandas.core.algorithms import factorize, take, take_1d, unique1d
+from pandas.core.base import NoNewAttributesMixin, PandasObject, _shared_docs
+from pandas.core.config import get_option
 from pandas.core.dtypes.cast import (
     coerce_indexer_dtype, maybe_infer_to_datetimelike)
 from pandas.core.dtypes.common import (
@@ -26,19 +28,13 @@
     ABCCategoricalIndex, ABCIndexClass, ABCSeries)
 from pandas.core.dtypes.inference import is_hashable
 from pandas.core.dtypes.missing import isna, notna
-
-from pandas.core.accessor import PandasDelegate, delegate_names
-import pandas.core.algorithms as algorithms
-from pandas.core.algorithms import factorize, take, take_1d, unique1d
-from pandas.core.base import NoNewAttributesMixin, PandasObject, _shared_docs
-import pandas.core.common as com
-from pandas.core.config import get_option
 from pandas.core.missing import interpolate_2d
 from pandas.core.sorting import nargsort
-
 from pandas.io.formats import console
 from pandas.io.formats.terminal import get_terminal_size
-
+from pandas.util._decorators import (
+    Appender, Substitution, cache_readonly, deprecate_kwarg)
+from pandas.util._validators import validate_bool_kwarg, validate_fillna_kwargs
 from .base import ExtensionArray
 
 _take_msg = textwrap.dedent("""\
@@ -1285,7 +1281,9 @@ def shift(self, periods, fill_value=None):
             elif fill_value in self.categories:
                 fill_value = self.categories.get_loc(fill_value)
             else:
-                raise ValueError("'fill_value={}' is not present in this Categorical's categories".format(fill_value))
+                raise ValueError("'fill_value={}' is not present "
+                                 "in this Categorical's "
+                                 "categories".format(fill_value))
             if periods > 0:
                 codes[:periods] = fill_value
             else:

From bbfe7f9387a425590702cd4b74bb0b370d6cd021 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Sun, 9 Dec 2018 03:34:44 +0200
Subject: [PATCH 028/108] !U fix indents

---
 pandas/tests/frame/test_timeseries.py | 27 ++++++++++-----------------
 1 file changed, 10 insertions(+), 17 deletions(-)

diff --git a/pandas/tests/frame/test_timeseries.py b/pandas/tests/frame/test_timeseries.py
index 346b56c9a9d69..e16e6bf6cb6d5 100644
--- a/pandas/tests/frame/test_timeseries.py
+++ b/pandas/tests/frame/test_timeseries.py
@@ -4,25 +4,18 @@
 
 from datetime import datetime, time
 
+import numpy as np
 import pytest
-
 from numpy.random import randn
-import numpy as np
 
-from pandas import (DataFrame, Series, Index,
-                    Timestamp, DatetimeIndex, MultiIndex,
-                    to_datetime, date_range, period_range)
 import pandas as pd
 import pandas.tseries.offsets as offsets
-
-from pandas.util.testing import (assert_series_equal,
-                                 assert_frame_equal,
-                                 assert_index_equal)
-
 import pandas.util.testing as tm
+from pandas import (DataFrame, DatetimeIndex, Index, MultiIndex, Series, Timestamp, date_range, period_range,
+                    to_datetime)
 from pandas.compat import product
-
 from pandas.tests.frame.common import TestData
+from pandas.util.testing import (assert_frame_equal, assert_index_equal, assert_series_equal)
 
 
 @pytest.fixture(params=product([True, False], [True, False]))
@@ -324,15 +317,15 @@ def test_shift_fill_value(self):
         # GH #24128
         df = DataFrame([1, 2, 3, 4, 5],
                        index=date_range('1/1/2000', periods=5, freq='H'))
-        expected = DataFrame([0, 1, 2, 3, 4],
-                       index=date_range('1/1/2000', periods=5, freq='H'))
+        exp = DataFrame([0, 1, 2, 3, 4],
+                        index=date_range('1/1/2000', periods=5, freq='H'))
         result = df.shift(1, fill_value=0)
-        assert_frame_equal(result, expected)
+        assert_frame_equal(result, exp)
 
-        expected = DataFrame([0, 0, 1, 2, 3],
-                       index=date_range('1/1/2000', periods=5, freq='H'))
+        exp = DataFrame([0, 0, 1, 2, 3],
+                        index=date_range('1/1/2000', periods=5, freq='H'))
         result = df.shift(2, fill_value=0)
-        assert_frame_equal(result, expected)
+        assert_frame_equal(result, exp)
 
     def test_shift_empty(self):
         # Regression test for #8019

From ef55afbe6cc44cfabe03381ad2f6dae8907c103f Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Sun, 9 Dec 2018 03:35:17 +0200
Subject: [PATCH 029/108] !U fix indents

---
 pandas/tests/series/test_timeseries.py | 26 ++++++++++++--------------
 1 file changed, 12 insertions(+), 14 deletions(-)

diff --git a/pandas/tests/series/test_timeseries.py b/pandas/tests/series/test_timeseries.py
index f7bd5e7936a30..67a190705fef8 100644
--- a/pandas/tests/series/test_timeseries.py
+++ b/pandas/tests/series/test_timeseries.py
@@ -6,24 +6,22 @@
 import numpy as np
 import pytest
 
-from pandas._libs.tslib import iNaT
-from pandas.compat import StringIO, lrange, product
-from pandas.errors import NullFrequencyError
-import pandas.util._test_decorators as td
-
 import pandas as pd
+import pandas.util._test_decorators as td
+import pandas.util.testing as tm
 from pandas import (
     DataFrame, Index, NaT, Series, Timestamp, concat, date_range, offsets,
     timedelta_range, to_datetime)
+from pandas._libs.tslib import iNaT
+from pandas.compat import StringIO, lrange, product
 from pandas.core.indexes.datetimes import DatetimeIndex
 from pandas.core.indexes.timedeltas import TimedeltaIndex
+from pandas.errors import NullFrequencyError
 from pandas.tests.series.common import TestData
-import pandas.util.testing as tm
+from pandas.tseries.offsets import BDay, BMonthEnd
 from pandas.util.testing import (
     assert_almost_equal, assert_frame_equal, assert_series_equal)
 
-from pandas.tseries.offsets import BDay, BMonthEnd
-
 
 def _simple_ts(start, end, freq='D'):
     rng = date_range(start, end, freq=freq)
@@ -140,16 +138,16 @@ def test_shift_fill_value(self):
         tm.assert_index_equal(result.index, exp_index)
         tm.assert_numpy_array_equal(result.values, ts.values)
 
-        expected = Series([0.0, 1.0, 2.0, 3.0, 4.0],
-                    index=date_range('1/1/2000', periods=5, freq='H'))
+        exp = Series([0.0, 1.0, 2.0, 3.0, 4.0],
+                     index=date_range('1/1/2000', periods=5, freq='H'))
         # check that fill value works
         result = ts.shift(1, fill_value=0.0)
-        tm.assert_series_equal(result, expected)
+        tm.assert_series_equal(result, exp)
 
-        expected = Series([0.0, 0.0, 1.0, 2.0, 3.0],
-                    index=date_range('1/1/2000', periods=5, freq='H'))
+        exp = Series([0.0, 0.0, 1.0, 2.0, 3.0],
+                     index=date_range('1/1/2000', periods=5, freq='H'))
         result = ts.shift(2, fill_value=0.0)
-        tm.assert_series_equal(result, expected)
+        tm.assert_series_equal(result, exp)
 
     def test_shift_dst(self):
         # GH 13926

From ce3d3c711d436d5dedba95e3a81ec26a9b994f20 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Sun, 9 Dec 2018 14:57:19 +0200
Subject: [PATCH 030/108] !U remove whitespaces

---
 pandas/core/generic.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/pandas/core/generic.py b/pandas/core/generic.py
index c569a75347adf..eb53292be7e96 100644
--- a/pandas/core/generic.py
+++ b/pandas/core/generic.py
@@ -8830,8 +8830,8 @@ def mask(self, cond, other=np.nan, inplace=False, axis=None, level=None,
         fill_value : object, optional
             the scalar value to use for newly introduced missing values.
             the default depends on the dtype of `self`. for numeric data,
-            ``np.nan`` is used. for datelike, ``pandas.nat`` is used.    
-            
+            ``np.nan`` is used. for datelike, ``pandas.nat`` is used.
+
             .. versionchanged:: 0.24.0
 
         Returns

From e6103a43328aab75c74fe0bbe0e3770c22e567d3 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Sun, 9 Dec 2018 14:57:48 +0200
Subject: [PATCH 031/108] !U remove whitespaces

---
 pandas/core/generic.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pandas/core/generic.py b/pandas/core/generic.py
index eb53292be7e96..ffdbed7134383 100644
--- a/pandas/core/generic.py
+++ b/pandas/core/generic.py
@@ -8868,7 +8868,7 @@ def mask(self, cond, other=np.nan, inplace=False, axis=None, level=None,
         2   NaN  15.0  18.0
         3   NaN  30.0  33.0
         4   NaN  45.0  48.0
-        
+
         >>> df.shift(periods=3, fill_value=0.0)
            Col1  Col2  Col3
         0   0.0   0.0   0.0

From d18b6b74525b9b95cbd90dff4e7fa8fde712fe9a Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Sun, 9 Dec 2018 14:58:03 +0200
Subject: [PATCH 032/108] !U fix the line width

---
 pandas/core/groupby/groupby.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/pandas/core/groupby/groupby.py b/pandas/core/groupby/groupby.py
index 327ab4a788b6d..197e3a5d004f2 100644
--- a/pandas/core/groupby/groupby.py
+++ b/pandas/core/groupby/groupby.py
@@ -2005,7 +2005,8 @@ def shift(self, periods=1, freq=None, axis=0, fill_value=None):
         """
 
         if freq is not None or axis != 0:
-            return self.apply(lambda x: x.shift(periods, freq, axis, fill_value))
+            return self.apply(lambda x: x.shift(periods, freq,
+                                                axis, fill_value))
 
         return self._get_cythonized_result('group_shift_indexer',
                                            self.grouper, cython_dtype=np.int64,

From 931df66cdcb4743c86cde33e03d20104a3470867 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Sun, 9 Dec 2018 14:58:54 +0200
Subject: [PATCH 033/108] !U fix the imports width

---
 pandas/tests/frame/test_timeseries.py | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/pandas/tests/frame/test_timeseries.py b/pandas/tests/frame/test_timeseries.py
index e16e6bf6cb6d5..efcc8250b3352 100644
--- a/pandas/tests/frame/test_timeseries.py
+++ b/pandas/tests/frame/test_timeseries.py
@@ -11,11 +11,13 @@
 import pandas as pd
 import pandas.tseries.offsets as offsets
 import pandas.util.testing as tm
-from pandas import (DataFrame, DatetimeIndex, Index, MultiIndex, Series, Timestamp, date_range, period_range,
+from pandas import (DataFrame, DatetimeIndex, Index, MultiIndex, Series,
+                    Timestamp, date_range, period_range,
                     to_datetime)
 from pandas.compat import product
 from pandas.tests.frame.common import TestData
-from pandas.util.testing import (assert_frame_equal, assert_index_equal, assert_series_equal)
+from pandas.util.testing import (assert_frame_equal, assert_index_equal,
+                                 assert_series_equal)
 
 
 @pytest.fixture(params=product([True, False], [True, False]))

From 81c01bcaee0e46f065be216078ebcd6b502936e4 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Sun, 9 Dec 2018 15:05:41 +0200
Subject: [PATCH 034/108] !U restore the fill_value

---
 pandas/core/arrays/base.py | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/pandas/core/arrays/base.py b/pandas/core/arrays/base.py
index b2ad290314e25..55137873974eb 100644
--- a/pandas/core/arrays/base.py
+++ b/pandas/core/arrays/base.py
@@ -483,6 +483,10 @@ def shift(self, periods=1, fill_value=None):
         # stored in an instance of your ExtensionArray with `self.dtype`.
         if not len(self) or periods == 0:
             return self.copy()
+
+        if fill_value is None:
+            fill_value = self.dtype.na_value
+
         empty = self._from_sequence(
             [fill_value] * min(abs(periods), len(self)),
             dtype=self.dtype

From 4ae4d0bbfbd823887a6991a88e3fe83a8392d4ec Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Sun, 9 Dec 2018 15:10:50 +0200
Subject: [PATCH 035/108] !U revert imports

---
 pandas/core/arrays/categorical.py | 21 +++++++++++----------
 1 file changed, 11 insertions(+), 10 deletions(-)

diff --git a/pandas/core/arrays/categorical.py b/pandas/core/arrays/categorical.py
index 902d7c25b059e..149f8e5ac5379 100644
--- a/pandas/core/arrays/categorical.py
+++ b/pandas/core/arrays/categorical.py
@@ -5,16 +5,13 @@
 
 import numpy as np
 
-import pandas.compat as compat
-import pandas.core.algorithms as algorithms
-import pandas.core.common as com
 from pandas._libs import algos as libalgos, lib
+import pandas.compat as compat
 from pandas.compat import lzip, u
 from pandas.compat.numpy import function as nv
-from pandas.core.accessor import PandasDelegate, delegate_names
-from pandas.core.algorithms import factorize, take, take_1d, unique1d
-from pandas.core.base import NoNewAttributesMixin, PandasObject, _shared_docs
-from pandas.core.config import get_option
+from pandas.util._decorators import (
+    Appender, Substitution, cache_readonly, deprecate_kwarg)
+from pandas.util._validators import validate_bool_kwarg, validate_fillna_kwargs
 from pandas.core.dtypes.cast import (
     coerce_indexer_dtype, maybe_infer_to_datetimelike)
 from pandas.core.dtypes.common import (
@@ -28,13 +25,17 @@
     ABCCategoricalIndex, ABCIndexClass, ABCSeries)
 from pandas.core.dtypes.inference import is_hashable
 from pandas.core.dtypes.missing import isna, notna
+
+from pandas.core.accessor import PandasDelegate, delegate_names
+import pandas.core.algorithms as algorithms
+from pandas.core.algorithms import factorize, take, take_1d, unique1d
+from pandas.core.base import NoNewAttributesMixin, PandasObject, _shared_docs
+import pandas.core.common as com
+from pandas.core.config import get_option
 from pandas.core.missing import interpolate_2d
 from pandas.core.sorting import nargsort
 from pandas.io.formats import console
 from pandas.io.formats.terminal import get_terminal_size
-from pandas.util._decorators import (
-    Appender, Substitution, cache_readonly, deprecate_kwarg)
-from pandas.util._validators import validate_bool_kwarg, validate_fillna_kwargs
 from .base import ExtensionArray
 
 _take_msg = textwrap.dedent("""\

From d4d43a388d0f9255cdc032126545abcdb617f5eb Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Sun, 9 Dec 2018 15:13:31 +0200
Subject: [PATCH 036/108] !U revert new lines deletion

---
 pandas/core/arrays/categorical.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/pandas/core/arrays/categorical.py b/pandas/core/arrays/categorical.py
index 149f8e5ac5379..3377ce91bae60 100644
--- a/pandas/core/arrays/categorical.py
+++ b/pandas/core/arrays/categorical.py
@@ -12,6 +12,7 @@
 from pandas.util._decorators import (
     Appender, Substitution, cache_readonly, deprecate_kwarg)
 from pandas.util._validators import validate_bool_kwarg, validate_fillna_kwargs
+
 from pandas.core.dtypes.cast import (
     coerce_indexer_dtype, maybe_infer_to_datetimelike)
 from pandas.core.dtypes.common import (
@@ -34,8 +35,10 @@
 from pandas.core.config import get_option
 from pandas.core.missing import interpolate_2d
 from pandas.core.sorting import nargsort
+
 from pandas.io.formats import console
 from pandas.io.formats.terminal import get_terminal_size
+
 from .base import ExtensionArray
 
 _take_msg = textwrap.dedent("""\

From 136616191e2c4f9d0ceed5fc5baa3248238d2434 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Sun, 9 Dec 2018 15:16:13 +0200
Subject: [PATCH 037/108] !U revert changes in imports

---
 pandas/core/generic.py | 30 +++++++++++++++---------------
 1 file changed, 15 insertions(+), 15 deletions(-)

diff --git a/pandas/core/generic.py b/pandas/core/generic.py
index cb28cde5188c3..46d957d9c6a7a 100644
--- a/pandas/core/generic.py
+++ b/pandas/core/generic.py
@@ -9,41 +9,41 @@
 
 import numpy as np
 
-import pandas as pd
-import pandas.compat as compat
-import pandas.core.algorithms as algos
-import pandas.core.common as com
-import pandas.core.indexing as indexing
 from pandas._libs import Timestamp, iNaT, properties
+import pandas.compat as compat
 from pandas.compat import (
     cPickle as pkl, isidentifier, lrange, lzip, map, set_function_name,
     string_types, to_str, zip)
 from pandas.compat.numpy import function as nv
-from pandas.core import config, missing, nanops
-from pandas.core.base import PandasObject, SelectionMixin
+from pandas.errors import AbstractMethodError
+from pandas.util._decorators import (
+    Appender, Substitution, rewrite_axis_style_signature)
+from pandas.util._validators import validate_bool_kwarg, validate_fillna_kwargs
 from pandas.core.dtypes.cast import maybe_promote, maybe_upcast_putmask
 from pandas.core.dtypes.common import (
     ensure_int64, ensure_object, is_bool, is_bool_dtype,
-    is_datetime64_any_dtype, is_datetime64tz_dtype, is_dict_like,
-    is_extension_array_dtype, is_integer, is_list_like, is_number,
-    is_numeric_dtype, is_object_dtype, is_period_arraylike, is_re_compilable,
-    is_scalar, is_timedelta64_dtype, pandas_dtype)
+     is_datetime64_any_dtype, is_datetime64tz_dtype, is_dict_like,
+     is_extension_array_dtype, is_integer, is_list_like, is_number,
+     is_numeric_dtype, is_object_dtype, is_period_arraylike, is_re_compilable,
+     is_scalar, is_timedelta64_dtype, pandas_dtype)
 from pandas.core.dtypes.generic import ABCDataFrame, ABCPanel, ABCSeries
 from pandas.core.dtypes.inference import is_hashable
 from pandas.core.dtypes.missing import isna, notna
+import pandas as pd
+from pandas.core import config, missing, nanops
+import pandas.core.algorithms as algos
+from pandas.core.base import PandasObject, SelectionMixin
+import pandas.core.common as com
 from pandas.core.index import (
     Index, InvalidIndexError, MultiIndex, RangeIndex, ensure_index)
 from pandas.core.indexes.datetimes import DatetimeIndex
 from pandas.core.indexes.period import Period, PeriodIndex
+import pandas.core.indexing as indexing
 from pandas.core.internals import BlockManager
 from pandas.core.ops import _align_method_FRAME
-from pandas.errors import AbstractMethodError
 from pandas.io.formats.format import DataFrameFormatter, format_percentiles
 from pandas.io.formats.printing import pprint_thing
 from pandas.tseries.frequencies import to_offset
-from pandas.util._decorators import (
-    Appender, Substitution, rewrite_axis_style_signature)
-from pandas.util._validators import validate_bool_kwarg, validate_fillna_kwargs
 
 # goal is to be able to define the docs close to function, while still being
 # able to share

From 2643aa5e792be0d050d7c8ceba05043352b67f2d Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Sun, 9 Dec 2018 15:18:31 +0200
Subject: [PATCH 038/108] !U revert changes in imports

---
 pandas/core/internals/blocks.py | 35 ++++++++++++++++-----------------
 1 file changed, 17 insertions(+), 18 deletions(-)

diff --git a/pandas/core/internals/blocks.py b/pandas/core/internals/blocks.py
index ded799ed8309d..3df90bc70cd01 100644
--- a/pandas/core/internals/blocks.py
+++ b/pandas/core/internals/blocks.py
@@ -1,45 +1,44 @@
 # -*- coding: utf-8 -*-
+from datetime import date, datetime, timedelta
 import functools
 import inspect
 import re
 import warnings
-from datetime import date, datetime, timedelta
 
-import numpy as np
+ import numpy as np
 
-import pandas.compat as compat
-import pandas.core.algorithms as algos
-import pandas.core.common as com
-import pandas.core.dtypes.concat as _concat
-import pandas.core.missing as missing
 from pandas._libs import internals as libinternals, lib, tslib, tslibs
 from pandas._libs.tslibs import Timedelta, conversion
+import pandas.compat as compat
 from pandas.compat import range, zip
-from pandas.core.arrays import Categorical, ExtensionArray
-from pandas.core.base import PandasObject
+from pandas.util._validators import validate_bool_kwarg
 from pandas.core.dtypes.cast import (
     astype_nansafe, find_common_type, infer_dtype_from,
     infer_dtype_from_scalar, maybe_convert_objects, maybe_downcast_to_dtype,
-    maybe_infer_dtype_type, maybe_promote, maybe_upcast, soft_convert_objects)
+     maybe_infer_dtype_type, maybe_promote, maybe_upcast, soft_convert_objects)
 from pandas.core.dtypes.common import (
-    _NS_DTYPE, _TD_DTYPE, ensure_platform_int, is_bool_dtype, is_categorical,
-    is_categorical_dtype, is_datetime64_dtype, is_datetime64tz_dtype,
-    is_dtype_equal, is_extension_array_dtype, is_extension_type,
-    is_float_dtype, is_integer, is_integer_dtype, is_interval_dtype,
-    is_list_like, is_numeric_v_string_like, is_object_dtype, is_period_dtype,
-    is_re, is_re_compilable, is_sparse, is_timedelta64_dtype, pandas_dtype)
+     _NS_DTYPE, _TD_DTYPE, ensure_platform_int, is_bool_dtype, is_categorical,
+     is_categorical_dtype, is_datetime64_dtype, is_datetime64tz_dtype,
+     is_dtype_equal, is_extension_array_dtype, is_extension_type,
+     is_float_dtype, is_integer, is_integer_dtype, is_interval_dtype,
+     is_list_like, is_numeric_v_string_like, is_object_dtype, is_period_dtype,
+     is_re, is_re_compilable, is_sparse, is_timedelta64_dtype, pandas_dtype)
 import pandas.core.dtypes.concat as _concat
 from pandas.core.dtypes.dtypes import (
-    CategoricalDtype, DatetimeTZDtype, ExtensionDtype, PandasExtensionDtype)
+     CategoricalDtype, DatetimeTZDtype, ExtensionDtype, PandasExtensionDtype)
 from pandas.core.dtypes.generic import (
     ABCDatetimeIndex, ABCExtensionArray, ABCIndexClass, ABCSeries)
 from pandas.core.dtypes.missing import (
     _isna_compat, array_equivalent, is_null_datelike_scalar, isna, notna)
+import pandas.core.algorithms as algos
+from pandas.core.arrays import Categorical, ExtensionArray
+from pandas.core.base import PandasObject
+import pandas.core.common as com
 from pandas.core.indexes.datetimes import DatetimeIndex
 from pandas.core.indexes.timedeltas import TimedeltaIndex
 from pandas.core.indexing import check_setitem_lengths
+import pandas.core.missing as missing
 from pandas.io.formats.printing import pprint_thing
-from pandas.util._validators import validate_bool_kwarg
 
 
 class Block(PandasObject):

From c010413e1fd5c733c55b17863dff3ce51e22e9ab Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Sun, 9 Dec 2018 15:20:23 +0200
Subject: [PATCH 039/108] !U revert changes in imports

---
 pandas/core/generic.py | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/pandas/core/generic.py b/pandas/core/generic.py
index 46d957d9c6a7a..13e71c566511b 100644
--- a/pandas/core/generic.py
+++ b/pandas/core/generic.py
@@ -19,16 +19,18 @@
 from pandas.util._decorators import (
     Appender, Substitution, rewrite_axis_style_signature)
 from pandas.util._validators import validate_bool_kwarg, validate_fillna_kwargs
+
 from pandas.core.dtypes.cast import maybe_promote, maybe_upcast_putmask
 from pandas.core.dtypes.common import (
     ensure_int64, ensure_object, is_bool, is_bool_dtype,
-     is_datetime64_any_dtype, is_datetime64tz_dtype, is_dict_like,
-     is_extension_array_dtype, is_integer, is_list_like, is_number,
-     is_numeric_dtype, is_object_dtype, is_period_arraylike, is_re_compilable,
-     is_scalar, is_timedelta64_dtype, pandas_dtype)
+    is_datetime64_any_dtype, is_datetime64tz_dtype, is_dict_like,
+    is_extension_array_dtype, is_integer, is_list_like, is_number,
+    is_numeric_dtype, is_object_dtype, is_period_arraylike, is_re_compilable,
+    is_scalar, is_timedelta64_dtype, pandas_dtype)
 from pandas.core.dtypes.generic import ABCDataFrame, ABCPanel, ABCSeries
 from pandas.core.dtypes.inference import is_hashable
 from pandas.core.dtypes.missing import isna, notna
+
 import pandas as pd
 from pandas.core import config, missing, nanops
 import pandas.core.algorithms as algos
@@ -41,6 +43,7 @@
 import pandas.core.indexing as indexing
 from pandas.core.internals import BlockManager
 from pandas.core.ops import _align_method_FRAME
+
 from pandas.io.formats.format import DataFrameFormatter, format_percentiles
 from pandas.io.formats.printing import pprint_thing
 from pandas.tseries.frequencies import to_offset

From 689bf8edc94cd4cd506f58a599296f43e968b587 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Sun, 9 Dec 2018 15:22:27 +0200
Subject: [PATCH 040/108] !U revert imports

---
 pandas/core/groupby/groupby.py | 24 +++++++++++++-----------
 1 file changed, 13 insertions(+), 11 deletions(-)

diff --git a/pandas/core/groupby/groupby.py b/pandas/core/groupby/groupby.py
index 105c7b5253c3d..e6d7dc29b2d30 100644
--- a/pandas/core/groupby/groupby.py
+++ b/pandas/core/groupby/groupby.py
@@ -8,36 +8,38 @@ class providing the base-class of operations.
 """
 
 import collections
+from contextlib import contextmanager
 import datetime
+from functools import partial, wraps
 import types
 import warnings
-from contextlib import contextmanager
-from functools import partial, wraps
 
 import numpy as np
 
-import pandas.compat as compat
-import pandas.core.algorithms as algorithms
-import pandas.core.common as com
 from pandas._libs import Timestamp, groupby as libgroupby
+import pandas.compat as compat
 from pandas.compat import callable, range, set_function_name, zip
 from pandas.compat.numpy import function as nv
-from pandas.core.base import (
-    DataError, GroupByError, PandasObject, SelectionMixin, SpecificationError)
-from pandas.core.config import option_context
+from pandas.errors import AbstractMethodError
+from pandas.util._decorators import Appender, Substitution, cache_readonly
+from pandas.util._validators import validate_kwargs
+
 from pandas.core.dtypes.cast import maybe_downcast_to_dtype
 from pandas.core.dtypes.common import (
     ensure_float, is_extension_array_dtype, is_numeric_dtype, is_scalar)
 from pandas.core.dtypes.missing import isna, notna
+
+import pandas.core.algorithms as algorithms
+from pandas.core.base import (
+    DataError, GroupByError, PandasObject, SelectionMixin, SpecificationError)
+import pandas.core.common as com
+from pandas.core.config import option_context
 from pandas.core.frame import DataFrame
 from pandas.core.generic import NDFrame
 from pandas.core.groupby import base
 from pandas.core.index import Index, MultiIndex
 from pandas.core.series import Series
 from pandas.core.sorting import get_group_index_sorter
-from pandas.errors import AbstractMethodError
-from pandas.util._decorators import Appender, Substitution, cache_readonly
-from pandas.util._validators import validate_kwargs
 
 _doc_template = """
         See Also

From 463964bdb9a9d3ca0d11238a90a39983b81a3f6d Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Sun, 9 Dec 2018 15:25:34 +0200
Subject: [PATCH 041/108] !U revert imports

---
 pandas/core/internals/blocks.py | 36 ++++++++++++++++-----------------
 1 file changed, 18 insertions(+), 18 deletions(-)

diff --git a/pandas/core/internals/blocks.py b/pandas/core/internals/blocks.py
index 3df90bc70cd01..14a53413a96cd 100644
--- a/pandas/core/internals/blocks.py
+++ b/pandas/core/internals/blocks.py
@@ -1,44 +1,44 @@
 # -*- coding: utf-8 -*-
-from datetime import date, datetime, timedelta
 import functools
 import inspect
 import re
 import warnings
+from datetime import date, datetime, timedelta
 
- import numpy as np
+import numpy as np
 
+import pandas.compat as compat
+import pandas.core.algorithms as algos
+import pandas.core.common as com
+import pandas.core.dtypes.concat as _concat
+import pandas.core.missing as missing
 from pandas._libs import internals as libinternals, lib, tslib, tslibs
 from pandas._libs.tslibs import Timedelta, conversion
-import pandas.compat as compat
 from pandas.compat import range, zip
-from pandas.util._validators import validate_bool_kwarg
+from pandas.core.arrays import Categorical, ExtensionArray
+from pandas.core.base import PandasObject
 from pandas.core.dtypes.cast import (
     astype_nansafe, find_common_type, infer_dtype_from,
     infer_dtype_from_scalar, maybe_convert_objects, maybe_downcast_to_dtype,
-     maybe_infer_dtype_type, maybe_promote, maybe_upcast, soft_convert_objects)
+    maybe_infer_dtype_type, maybe_promote, maybe_upcast, soft_convert_objects)
 from pandas.core.dtypes.common import (
-     _NS_DTYPE, _TD_DTYPE, ensure_platform_int, is_bool_dtype, is_categorical,
-     is_categorical_dtype, is_datetime64_dtype, is_datetime64tz_dtype,
-     is_dtype_equal, is_extension_array_dtype, is_extension_type,
-     is_float_dtype, is_integer, is_integer_dtype, is_interval_dtype,
-     is_list_like, is_numeric_v_string_like, is_object_dtype, is_period_dtype,
-     is_re, is_re_compilable, is_sparse, is_timedelta64_dtype, pandas_dtype)
-import pandas.core.dtypes.concat as _concat
+    _NS_DTYPE, _TD_DTYPE, ensure_platform_int, is_bool_dtype, is_categorical,
+    is_categorical_dtype, is_datetime64_dtype, is_datetime64tz_dtype,
+    is_dtype_equal, is_extension_array_dtype, is_extension_type,
+    is_float_dtype, is_integer, is_integer_dtype, is_interval_dtype,
+    is_list_like, is_numeric_v_string_like, is_object_dtype, is_period_dtype,
+    is_re, is_re_compilable, is_sparse, is_timedelta64_dtype, pandas_dtype)
 from pandas.core.dtypes.dtypes import (
-     CategoricalDtype, DatetimeTZDtype, ExtensionDtype, PandasExtensionDtype)
+    CategoricalDtype, DatetimeTZDtype, ExtensionDtype, PandasExtensionDtype)
 from pandas.core.dtypes.generic import (
     ABCDatetimeIndex, ABCExtensionArray, ABCIndexClass, ABCSeries)
 from pandas.core.dtypes.missing import (
     _isna_compat, array_equivalent, is_null_datelike_scalar, isna, notna)
-import pandas.core.algorithms as algos
-from pandas.core.arrays import Categorical, ExtensionArray
-from pandas.core.base import PandasObject
-import pandas.core.common as com
 from pandas.core.indexes.datetimes import DatetimeIndex
 from pandas.core.indexes.timedeltas import TimedeltaIndex
 from pandas.core.indexing import check_setitem_lengths
-import pandas.core.missing as missing
 from pandas.io.formats.printing import pprint_thing
+from pandas.util._validators import validate_bool_kwarg
 
 
 class Block(PandasObject):

From b90b00f8ba49de4bc6cc092baaf21155a53afaa5 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Sun, 9 Dec 2018 15:27:38 +0200
Subject: [PATCH 042/108] !U revert imports

---
 pandas/tests/frame/test_timeseries.py | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/pandas/tests/frame/test_timeseries.py b/pandas/tests/frame/test_timeseries.py
index efcc8250b3352..e16e6bf6cb6d5 100644
--- a/pandas/tests/frame/test_timeseries.py
+++ b/pandas/tests/frame/test_timeseries.py
@@ -11,13 +11,11 @@
 import pandas as pd
 import pandas.tseries.offsets as offsets
 import pandas.util.testing as tm
-from pandas import (DataFrame, DatetimeIndex, Index, MultiIndex, Series,
-                    Timestamp, date_range, period_range,
+from pandas import (DataFrame, DatetimeIndex, Index, MultiIndex, Series, Timestamp, date_range, period_range,
                     to_datetime)
 from pandas.compat import product
 from pandas.tests.frame.common import TestData
-from pandas.util.testing import (assert_frame_equal, assert_index_equal,
-                                 assert_series_equal)
+from pandas.util.testing import (assert_frame_equal, assert_index_equal, assert_series_equal)
 
 
 @pytest.fixture(params=product([True, False], [True, False]))

From 18fab2fe511c7d1d2791bc41100aad3cb785e83a Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Sun, 9 Dec 2018 15:28:57 +0200
Subject: [PATCH 043/108] !U revert imports

---
 pandas/tests/frame/test_timeseries.py | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/pandas/tests/frame/test_timeseries.py b/pandas/tests/frame/test_timeseries.py
index e16e6bf6cb6d5..9bb632a2a3131 100644
--- a/pandas/tests/frame/test_timeseries.py
+++ b/pandas/tests/frame/test_timeseries.py
@@ -4,18 +4,24 @@
 
 from datetime import datetime, time
 
-import numpy as np
 import pytest
+
 from numpy.random import randn
+import numpy as np
 
+
+from pandas import (DataFrame, Series, Index,
+                    Timestamp, DatetimeIndex, MultiIndex,
+                    to_datetime, date_range, period_range)
 import pandas as pd
 import pandas.tseries.offsets as offsets
+
+from pandas.util.testing import (assert_series_equal,
+                                 assert_frame_equal,
+                                 assert_index_equal)
 import pandas.util.testing as tm
-from pandas import (DataFrame, DatetimeIndex, Index, MultiIndex, Series, Timestamp, date_range, period_range,
-                    to_datetime)
 from pandas.compat import product
 from pandas.tests.frame.common import TestData
-from pandas.util.testing import (assert_frame_equal, assert_index_equal, assert_series_equal)
 
 
 @pytest.fixture(params=product([True, False], [True, False]))

From cb0321552a564537bb718830fa866b3745164214 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Sun, 9 Dec 2018 15:29:30 +0200
Subject: [PATCH 044/108] !U revert imports

---
 pandas/tests/frame/test_timeseries.py | 1 -
 1 file changed, 1 deletion(-)

diff --git a/pandas/tests/frame/test_timeseries.py b/pandas/tests/frame/test_timeseries.py
index 9bb632a2a3131..dfdda880ab77c 100644
--- a/pandas/tests/frame/test_timeseries.py
+++ b/pandas/tests/frame/test_timeseries.py
@@ -9,7 +9,6 @@
 from numpy.random import randn
 import numpy as np
 
-
 from pandas import (DataFrame, Series, Index,
                     Timestamp, DatetimeIndex, MultiIndex,
                     to_datetime, date_range, period_range)

From c8242f3d0cf9b333acafc46d9760d8e4089a7bd1 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Sun, 9 Dec 2018 15:29:41 +0200
Subject: [PATCH 045/108] !U revert imports

---
 pandas/tests/frame/test_timeseries.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/pandas/tests/frame/test_timeseries.py b/pandas/tests/frame/test_timeseries.py
index dfdda880ab77c..02b83aaf5c131 100644
--- a/pandas/tests/frame/test_timeseries.py
+++ b/pandas/tests/frame/test_timeseries.py
@@ -18,8 +18,10 @@
 from pandas.util.testing import (assert_series_equal,
                                  assert_frame_equal,
                                  assert_index_equal)
+
 import pandas.util.testing as tm
 from pandas.compat import product
+
 from pandas.tests.frame.common import TestData
 
 

From 8e946cc21dcd71ca6ae6dec23e9d6e3b6a865bc7 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Sun, 9 Dec 2018 15:30:00 +0200
Subject: [PATCH 046/108] !U revert imports

---
 pandas/core/internals/blocks.py | 21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)

diff --git a/pandas/core/internals/blocks.py b/pandas/core/internals/blocks.py
index 14a53413a96cd..c000644f68929 100644
--- a/pandas/core/internals/blocks.py
+++ b/pandas/core/internals/blocks.py
@@ -1,22 +1,18 @@
 # -*- coding: utf-8 -*-
+from datetime import date, datetime, timedelta
 import functools
 import inspect
 import re
 import warnings
-from datetime import date, datetime, timedelta
 
 import numpy as np
 
-import pandas.compat as compat
-import pandas.core.algorithms as algos
-import pandas.core.common as com
-import pandas.core.dtypes.concat as _concat
-import pandas.core.missing as missing
 from pandas._libs import internals as libinternals, lib, tslib, tslibs
 from pandas._libs.tslibs import Timedelta, conversion
+import pandas.compat as compat
 from pandas.compat import range, zip
-from pandas.core.arrays import Categorical, ExtensionArray
-from pandas.core.base import PandasObject
+from pandas.util._validators import validate_bool_kwarg
+
 from pandas.core.dtypes.cast import (
     astype_nansafe, find_common_type, infer_dtype_from,
     infer_dtype_from_scalar, maybe_convert_objects, maybe_downcast_to_dtype,
@@ -28,17 +24,24 @@
     is_float_dtype, is_integer, is_integer_dtype, is_interval_dtype,
     is_list_like, is_numeric_v_string_like, is_object_dtype, is_period_dtype,
     is_re, is_re_compilable, is_sparse, is_timedelta64_dtype, pandas_dtype)
+
+import pandas.core.dtypes.concat as _concat
 from pandas.core.dtypes.dtypes import (
     CategoricalDtype, DatetimeTZDtype, ExtensionDtype, PandasExtensionDtype)
 from pandas.core.dtypes.generic import (
     ABCDatetimeIndex, ABCExtensionArray, ABCIndexClass, ABCSeries)
 from pandas.core.dtypes.missing import (
     _isna_compat, array_equivalent, is_null_datelike_scalar, isna, notna)
+import pandas.core.algorithms as algos
+from pandas.core.arrays import Categorical, ExtensionArray
+from pandas.core.base import PandasObject
+import pandas.core.common as com
 from pandas.core.indexes.datetimes import DatetimeIndex
 from pandas.core.indexes.timedeltas import TimedeltaIndex
 from pandas.core.indexing import check_setitem_lengths
+import pandas.core.missing as missing
+
 from pandas.io.formats.printing import pprint_thing
-from pandas.util._validators import validate_bool_kwarg
 
 
 class Block(PandasObject):

From 69e47f303e8813e01f24734e6b59236e5e2eb6db Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Sun, 9 Dec 2018 15:31:53 +0200
Subject: [PATCH 047/108] !U revert imports

---
 pandas/tests/series/test_timeseries.py | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/pandas/tests/series/test_timeseries.py b/pandas/tests/series/test_timeseries.py
index 67a190705fef8..aab378d9399d6 100644
--- a/pandas/tests/series/test_timeseries.py
+++ b/pandas/tests/series/test_timeseries.py
@@ -6,22 +6,24 @@
 import numpy as np
 import pytest
 
-import pandas as pd
+from pandas._libs.tslib import iNaT
+from pandas.compat import StringIO, lrange, product
+from pandas.errors import NullFrequencyError
 import pandas.util._test_decorators as td
-import pandas.util.testing as tm
+
+import pandas as pd
 from pandas import (
     DataFrame, Index, NaT, Series, Timestamp, concat, date_range, offsets,
     timedelta_range, to_datetime)
-from pandas._libs.tslib import iNaT
-from pandas.compat import StringIO, lrange, product
 from pandas.core.indexes.datetimes import DatetimeIndex
 from pandas.core.indexes.timedeltas import TimedeltaIndex
-from pandas.errors import NullFrequencyError
 from pandas.tests.series.common import TestData
-from pandas.tseries.offsets import BDay, BMonthEnd
+import pandas.util.testing as tm
 from pandas.util.testing import (
     assert_almost_equal, assert_frame_equal, assert_series_equal)
 
+from pandas.tseries.offsets import BDay, BMonthEnd
+
 
 def _simple_ts(start, end, freq='D'):
     rng = date_range(start, end, freq=freq)

From 8765bee2f2385cd04c0b719e9c0a2e5f8dbac782 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Sun, 9 Dec 2018 15:32:56 +0200
Subject: [PATCH 048/108] !U revert imports

---
 pandas/core/internals/blocks.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pandas/core/internals/blocks.py b/pandas/core/internals/blocks.py
index c000644f68929..eb9177e455ecb 100644
--- a/pandas/core/internals/blocks.py
+++ b/pandas/core/internals/blocks.py
@@ -24,7 +24,6 @@
     is_float_dtype, is_integer, is_integer_dtype, is_interval_dtype,
     is_list_like, is_numeric_v_string_like, is_object_dtype, is_period_dtype,
     is_re, is_re_compilable, is_sparse, is_timedelta64_dtype, pandas_dtype)
-
 import pandas.core.dtypes.concat as _concat
 from pandas.core.dtypes.dtypes import (
     CategoricalDtype, DatetimeTZDtype, ExtensionDtype, PandasExtensionDtype)
@@ -32,6 +31,7 @@
     ABCDatetimeIndex, ABCExtensionArray, ABCIndexClass, ABCSeries)
 from pandas.core.dtypes.missing import (
     _isna_compat, array_equivalent, is_null_datelike_scalar, isna, notna)
+
 import pandas.core.algorithms as algos
 from pandas.core.arrays import Categorical, ExtensionArray
 from pandas.core.base import PandasObject

From 9d10a6b073184f3193dc7feec94abda364fa9ed8 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Sun, 9 Dec 2018 18:36:52 +0200
Subject: [PATCH 049/108] !U remove doc from the doc

---
 pandas/core/arrays/base.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pandas/core/arrays/base.py b/pandas/core/arrays/base.py
index 55137873974eb..dd9c08053e0ed 100644
--- a/pandas/core/arrays/base.py
+++ b/pandas/core/arrays/base.py
@@ -462,7 +462,7 @@ def shift(self, periods=1, fill_value=None):
 
         fill_value : object, optional
             The scalar value to use for newly introduced missing values.
-            The default is ``self.dtype.na_value``.
+            The default is ``self.dtype.na_value``
 
             .. versionadded:: 0.24.0
 

From 6f4078ab3c7bf24c01c5dda618d7a73a0948a14a Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Sun, 9 Dec 2018 21:40:06 +0200
Subject: [PATCH 050/108] !U change description

---
 pandas/core/arrays/period.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pandas/core/arrays/period.py b/pandas/core/arrays/period.py
index 5a819d11080db..93ccceba20c6c 100644
--- a/pandas/core/arrays/period.py
+++ b/pandas/core/arrays/period.py
@@ -471,7 +471,7 @@ def shift(self, periods=1, fill_value=None):
         periods : int, default 1
             The number of periods to shift. Negative values are allowed
             for shifting backwards.
-        fill_value : None or value, default None (NaT)
+        fill_value : optional, default NaT
             .. versionadded:: 0.24.0
 
         Returns

From 4227dda4a4cfca33e9dee2e5c2fe337f4de54735 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Sun, 9 Dec 2018 21:42:04 +0200
Subject: [PATCH 051/108] !U change check for isna instead of is None

---
 pandas/core/arrays/categorical.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pandas/core/arrays/categorical.py b/pandas/core/arrays/categorical.py
index 3377ce91bae60..2c399e6ed6a7e 100644
--- a/pandas/core/arrays/categorical.py
+++ b/pandas/core/arrays/categorical.py
@@ -1280,7 +1280,7 @@ def shift(self, periods, fill_value=None):
             raise NotImplementedError("Categorical with ndim > 1.")
         if np.prod(codes.shape) and (periods != 0):
             codes = np.roll(codes, ensure_platform_int(periods), axis=0)
-            if fill_value is None:
+            if isna(fill_value):
                 fill_value = -1
             elif fill_value in self.categories:
                 fill_value = self.categories.get_loc(fill_value)

From ce721ae9174aa22e3a4ad327a9dd17d1da2979c4 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Sun, 9 Dec 2018 21:44:31 +0200
Subject: [PATCH 052/108] !U remove the -1 implementation detail

---
 pandas/core/arrays/categorical.py | 1 -
 1 file changed, 1 deletion(-)

diff --git a/pandas/core/arrays/categorical.py b/pandas/core/arrays/categorical.py
index 2c399e6ed6a7e..abae58f9d77eb 100644
--- a/pandas/core/arrays/categorical.py
+++ b/pandas/core/arrays/categorical.py
@@ -1265,7 +1265,6 @@ def shift(self, periods, fill_value=None):
             Number of periods to move, can be positive or negative
         fill_value : object, optional
             The scalar value to use for newly introduced missing values.
-            The default is ``-1``.
 
             .. versionadded:: 0.24.0
 

From c743004a5e34abaa6d6b6555b8b846152dcde736 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Sun, 9 Dec 2018 21:48:27 +0200
Subject: [PATCH 053/108] !U change doc description + added .. versionadded::
 0.24.0 tag

---
 pandas/core/groupby/groupby.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/pandas/core/groupby/groupby.py b/pandas/core/groupby/groupby.py
index e6d7dc29b2d30..68b4849c96cb1 100644
--- a/pandas/core/groupby/groupby.py
+++ b/pandas/core/groupby/groupby.py
@@ -2002,7 +2002,8 @@ def shift(self, periods=1, freq=None, axis=0, fill_value=None):
             number of periods to shift
         freq : frequency string
         axis : axis to shift, default 0
-        fill_value : None or value, default None (NaN)
+        fill_value : optional
+            .. versionadded:: 0.24.0
         """
 
         if freq is not None or axis != 0:

From 03e3bd47118501f999e395934155c3334728747d Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Tue, 11 Dec 2018 04:39:48 +0200
Subject: [PATCH 054/108] !U add test for sparse array shift with fill_value

---
 pandas/tests/arrays/sparse/test_array.py | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/pandas/tests/arrays/sparse/test_array.py b/pandas/tests/arrays/sparse/test_array.py
index b8cef92f6a6d4..110af9822a46a 100644
--- a/pandas/tests/arrays/sparse/test_array.py
+++ b/pandas/tests/arrays/sparse/test_array.py
@@ -262,6 +262,12 @@ def test_take_negative(self):
         exp = SparseArray(np.take(self.arr_data, [-4, -3, -2]))
         tm.assert_sp_array_equal(self.arr.take([-4, -3, -2]), exp)
 
+    def test_shift_fill_value(self):
+        sparse = SparseArray(np.array([1, 0, 0, 3, 0]))
+        res = sparse.shift(1, fill_value=0)
+        exp = SparseArray(np.array([0, 1, 0, 0, 3]))
+        tm.assert_sp_array_equal(res, exp)
+
     def test_bad_take(self):
         with pytest.raises(IndexError, match="bounds"):
             self.arr.take([11])

From e4313da00a89688e6716a89331f018184ca34c37 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Tue, 11 Dec 2018 04:53:11 +0200
Subject: [PATCH 055/108] !U add test for gorupby

---
 pandas/tests/groupby/test_groupby.py | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/pandas/tests/groupby/test_groupby.py b/pandas/tests/groupby/test_groupby.py
index 6d9f60df45ec8..e918b34b54d19 100644
--- a/pandas/tests/groupby/test_groupby.py
+++ b/pandas/tests/groupby/test_groupby.py
@@ -1617,6 +1617,23 @@ def test_group_shift_with_null_key():
     assert_frame_equal(result, expected)
 
 
+def test_group_shift_with_fill_value():
+    # GH #24128
+    n_rows = 1200
+    df = DataFrame([(i % 12, i % 3 if i % 3 else np.nan, i)
+                    for i in range(n_rows)], dtype=float,
+                   columns=["A", "B", "Z"], index=None)
+    g = df.groupby(["A", "B"])
+
+    expected = DataFrame([0] + [(i + 12 if i % 3 and i < n_rows - 12
+                           else np.nan)
+                          for i in range(n_rows)], dtype=float,
+                         columns=["Z"], index=None)
+    result = g.shift(1, fill_value=0.0)
+
+    assert_frame_equal(result, expected)
+
+
 def test_pivot_table_values_key_error():
     # This test is designed to replicate the error in issue #14938
     df = pd.DataFrame({'eventDate':

From 85d2b1698aff54f3b8111496c788a2be90727090 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Tue, 11 Dec 2018 04:53:26 +0200
Subject: [PATCH 056/108] !U add PR specification to the test

---
 pandas/tests/arrays/sparse/test_array.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/pandas/tests/arrays/sparse/test_array.py b/pandas/tests/arrays/sparse/test_array.py
index 110af9822a46a..45dcf55d4bf23 100644
--- a/pandas/tests/arrays/sparse/test_array.py
+++ b/pandas/tests/arrays/sparse/test_array.py
@@ -263,6 +263,7 @@ def test_take_negative(self):
         tm.assert_sp_array_equal(self.arr.take([-4, -3, -2]), exp)
 
     def test_shift_fill_value(self):
+        # GH #24128
         sparse = SparseArray(np.array([1, 0, 0, 3, 0]))
         res = sparse.shift(1, fill_value=0)
         exp = SparseArray(np.array([0, 1, 0, 0, 3]))

From da90e89fd8a831e15b146b8c0ad41dbee29fc071 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Tue, 11 Dec 2018 23:48:21 +0200
Subject: [PATCH 057/108] !U adjust types

---
 pandas/tests/arrays/sparse/test_array.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pandas/tests/arrays/sparse/test_array.py b/pandas/tests/arrays/sparse/test_array.py
index 45dcf55d4bf23..88624a2a992f3 100644
--- a/pandas/tests/arrays/sparse/test_array.py
+++ b/pandas/tests/arrays/sparse/test_array.py
@@ -266,7 +266,7 @@ def test_shift_fill_value(self):
         # GH #24128
         sparse = SparseArray(np.array([1, 0, 0, 3, 0]))
         res = sparse.shift(1, fill_value=0)
-        exp = SparseArray(np.array([0, 1, 0, 0, 3]))
+        exp = SparseArray(np.array([0, 1.0, 0, 0, 3.0]))
         tm.assert_sp_array_equal(res, exp)
 
     def test_bad_take(self):

From d71be8a07d75b5a3cdaf8719bef76caf32c99f3c Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Tue, 11 Dec 2018 23:49:34 +0200
Subject: [PATCH 058/108] !U fix the groupby test

---
 pandas/tests/groupby/test_groupby.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pandas/tests/groupby/test_groupby.py b/pandas/tests/groupby/test_groupby.py
index e918b34b54d19..8a62d038f5570 100644
--- a/pandas/tests/groupby/test_groupby.py
+++ b/pandas/tests/groupby/test_groupby.py
@@ -1627,7 +1627,7 @@ def test_group_shift_with_fill_value():
 
     expected = DataFrame([0] + [(i + 12 if i % 3 and i < n_rows - 12
                            else np.nan)
-                          for i in range(n_rows)], dtype=float,
+                          for i in range(n_rows-1)], dtype=float,
                          columns=["Z"], index=None)
     result = g.shift(1, fill_value=0.0)
 

From aca6c9cf65e0ed56d79a518b5c703664e1c9d67c Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Tue, 11 Dec 2018 23:54:47 +0200
Subject: [PATCH 059/108] !U add check for fill value in defining the type for
 result data set

---
 pandas/core/arrays/sparse.py | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/pandas/core/arrays/sparse.py b/pandas/core/arrays/sparse.py
index 8352fee3e32aa..ac8ec1596947e 100644
--- a/pandas/core/arrays/sparse.py
+++ b/pandas/core/arrays/sparse.py
@@ -892,7 +892,12 @@ def shift(self, periods=1, fill_value=None):
         if not len(self) or periods == 0:
             return self.copy()
 
-        subtype = np.result_type(np.nan, self.dtype.subtype)
+        if fill_value is None:
+            res_type = np.nan
+        else:
+            res_type = fill_value
+
+        subtype = np.result_type(res_type, self.dtype.subtype)
 
         if subtype != self.dtype.subtype:
             # just coerce up front

From 20361c70ded73468c8357c768f8009c03bfcc4df Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Tue, 11 Dec 2018 23:55:18 +0200
Subject: [PATCH 060/108] !U fix the types in the test

---
 pandas/tests/arrays/sparse/test_array.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pandas/tests/arrays/sparse/test_array.py b/pandas/tests/arrays/sparse/test_array.py
index 88624a2a992f3..45dcf55d4bf23 100644
--- a/pandas/tests/arrays/sparse/test_array.py
+++ b/pandas/tests/arrays/sparse/test_array.py
@@ -266,7 +266,7 @@ def test_shift_fill_value(self):
         # GH #24128
         sparse = SparseArray(np.array([1, 0, 0, 3, 0]))
         res = sparse.shift(1, fill_value=0)
-        exp = SparseArray(np.array([0, 1.0, 0, 0, 3.0]))
+        exp = SparseArray(np.array([0, 1, 0, 0, 3]))
         tm.assert_sp_array_equal(res, exp)
 
     def test_bad_take(self):

From 599ccb75d2d88e48472dc313f7a05271b92d85e7 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Wed, 12 Dec 2018 17:47:56 +0200
Subject: [PATCH 061/108] !U fix the test for groupby shift

---
 pandas/tests/groupby/test_groupby.py | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/pandas/tests/groupby/test_groupby.py b/pandas/tests/groupby/test_groupby.py
index 8a62d038f5570..feafccd63ec29 100644
--- a/pandas/tests/groupby/test_groupby.py
+++ b/pandas/tests/groupby/test_groupby.py
@@ -1620,16 +1620,16 @@ def test_group_shift_with_null_key():
 def test_group_shift_with_fill_value():
     # GH #24128
     n_rows = 1200
-    df = DataFrame([(i % 12, i % 3 if i % 3 else np.nan, i)
+    df = DataFrame([(i % 12, i % 3, i)
                     for i in range(n_rows)], dtype=float,
                    columns=["A", "B", "Z"], index=None)
     g = df.groupby(["A", "B"])
 
-    expected = DataFrame([0] + [(i + 12 if i % 3 and i < n_rows - 12
-                           else np.nan)
-                          for i in range(n_rows-1)], dtype=float,
+    expected = DataFrame([(i + 12 if i < n_rows - 12
+                           else 0)
+                          for i in range(n_rows)], dtype=float,
                          columns=["Z"], index=None)
-    result = g.shift(1, fill_value=0.0)
+    result = g.shift(-1, fill_value=0)
 
     assert_frame_equal(result, expected)
 

From 1ac273a9623826a7d8b0944117981954c93a68d1 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Wed, 12 Dec 2018 17:59:24 +0200
Subject: [PATCH 062/108] !U update notation of the base shift method

---
 pandas/core/arrays/base.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pandas/core/arrays/base.py b/pandas/core/arrays/base.py
index dd9c08053e0ed..8b1a062fb6736 100644
--- a/pandas/core/arrays/base.py
+++ b/pandas/core/arrays/base.py
@@ -445,7 +445,7 @@ def dropna(self):
         return self[~self.isna()]
 
     def shift(self, periods=1, fill_value=None):
-        # type: (int) -> ExtensionArray
+        # type: (int, object) -> ExtensionArray
         """
         Shift values by desired number.
 

From b2074a81c860aa95b982f38af892601fc5e5eb46 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Wed, 12 Dec 2018 17:59:43 +0200
Subject: [PATCH 063/108] !U test categorical shift

---
 pandas/tests/series/test_timeseries.py | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/pandas/tests/series/test_timeseries.py b/pandas/tests/series/test_timeseries.py
index aab378d9399d6..3e38625a94f4e 100644
--- a/pandas/tests/series/test_timeseries.py
+++ b/pandas/tests/series/test_timeseries.py
@@ -151,6 +151,15 @@ def test_shift_fill_value(self):
         result = ts.shift(2, fill_value=0.0)
         tm.assert_series_equal(result, exp)
 
+    def test_categorical_shift_fill_value(self):
+        ts = pd.Series(['a', 'b', 'c', 'd'], dtype="category")
+        res = ts.shift(1, fill_value='a')
+        exp = pd.Series(['a', 'a', 'b', 'c'], dtype="category")
+        tm.assert_series_equal(res, exp)
+
+        with pytest.raises(ValueError):
+            ts.shift(1, fill_value='f')
+
     def test_shift_dst(self):
         # GH 13926
         dates = date_range('2016-11-06', freq='H', periods=10, tz='US/Eastern')

From 0fe2f9591451869d84b75b649196e59c3d304197 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Wed, 12 Dec 2018 19:19:09 +0200
Subject: [PATCH 064/108] !U change the test for categorical

---
 pandas/tests/series/test_timeseries.py | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/pandas/tests/series/test_timeseries.py b/pandas/tests/series/test_timeseries.py
index 3e38625a94f4e..2c3f2d6fd90fb 100644
--- a/pandas/tests/series/test_timeseries.py
+++ b/pandas/tests/series/test_timeseries.py
@@ -154,8 +154,7 @@ def test_shift_fill_value(self):
     def test_categorical_shift_fill_value(self):
         ts = pd.Series(['a', 'b', 'c', 'd'], dtype="category")
         res = ts.shift(1, fill_value='a')
-        exp = pd.Series(['a', 'a', 'b', 'c'], dtype="category")
-        tm.assert_series_equal(res, exp)
+        tm.assert_equal(np.array(list(res.values)), np.array([ts.values[0]]+list(ts.values[:-1])))
 
         with pytest.raises(ValueError):
             ts.shift(1, fill_value='f')

From 7d33f21a049337f21e0f7be479b9775bacc2e6ec Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Wed, 12 Dec 2018 20:04:17 +0200
Subject: [PATCH 065/108] !U add check for fill value is not None

---
 pandas/core/groupby/groupby.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pandas/core/groupby/groupby.py b/pandas/core/groupby/groupby.py
index 68b4849c96cb1..3a158d394d375 100644
--- a/pandas/core/groupby/groupby.py
+++ b/pandas/core/groupby/groupby.py
@@ -2006,7 +2006,7 @@ def shift(self, periods=1, freq=None, axis=0, fill_value=None):
             .. versionadded:: 0.24.0
         """
 
-        if freq is not None or axis != 0:
+        if freq is not None or axis != 0 or fill_value is not None:
             return self.apply(lambda x: x.shift(periods, freq,
                                                 axis, fill_value))
 

From 578859b32d0b68d91ab954e61e1ae32b3376dda6 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Wed, 12 Dec 2018 20:04:37 +0200
Subject: [PATCH 066/108] !U change n_rows to smaller value

---
 pandas/tests/groupby/test_groupby.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pandas/tests/groupby/test_groupby.py b/pandas/tests/groupby/test_groupby.py
index feafccd63ec29..8d6fac81bb826 100644
--- a/pandas/tests/groupby/test_groupby.py
+++ b/pandas/tests/groupby/test_groupby.py
@@ -1619,7 +1619,7 @@ def test_group_shift_with_null_key():
 
 def test_group_shift_with_fill_value():
     # GH #24128
-    n_rows = 1200
+    n_rows = 24
     df = DataFrame([(i % 12, i % 3, i)
                     for i in range(n_rows)], dtype=float,
                    columns=["A", "B", "Z"], index=None)

From a016df3ef073c9fde4bbc3d09bf90b308f804fbf Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Wed, 12 Dec 2018 22:46:37 +0200
Subject: [PATCH 067/108] !U select Z column

---
 pandas/tests/groupby/test_groupby.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pandas/tests/groupby/test_groupby.py b/pandas/tests/groupby/test_groupby.py
index 8d6fac81bb826..d2fac24433ab5 100644
--- a/pandas/tests/groupby/test_groupby.py
+++ b/pandas/tests/groupby/test_groupby.py
@@ -1629,7 +1629,7 @@ def test_group_shift_with_fill_value():
                            else 0)
                           for i in range(n_rows)], dtype=float,
                          columns=["Z"], index=None)
-    result = g.shift(-1, fill_value=0)
+    result = g.shift(-1, fill_value=0)["Z"]
 
     assert_frame_equal(result, expected)
 

From 39473942e61f7421ae7e19554598de0c451e2d26 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Wed, 12 Dec 2018 22:46:54 +0200
Subject: [PATCH 068/108] !U select as DataFrame

---
 pandas/tests/groupby/test_groupby.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pandas/tests/groupby/test_groupby.py b/pandas/tests/groupby/test_groupby.py
index d2fac24433ab5..e9de46bba03f1 100644
--- a/pandas/tests/groupby/test_groupby.py
+++ b/pandas/tests/groupby/test_groupby.py
@@ -1629,7 +1629,7 @@ def test_group_shift_with_fill_value():
                            else 0)
                           for i in range(n_rows)], dtype=float,
                          columns=["Z"], index=None)
-    result = g.shift(-1, fill_value=0)["Z"]
+    result = g.shift(-1, fill_value=0)[["Z"]]
 
     assert_frame_equal(result, expected)
 

From b266a50d1c3c0bc264386d0dcb3d2b3eb3c33a84 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Wed, 12 Dec 2018 23:28:23 +0200
Subject: [PATCH 069/108] !U fix formatting errors

---
 pandas/tests/series/test_timeseries.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/pandas/tests/series/test_timeseries.py b/pandas/tests/series/test_timeseries.py
index 2c3f2d6fd90fb..c571524836d8a 100644
--- a/pandas/tests/series/test_timeseries.py
+++ b/pandas/tests/series/test_timeseries.py
@@ -154,7 +154,8 @@ def test_shift_fill_value(self):
     def test_categorical_shift_fill_value(self):
         ts = pd.Series(['a', 'b', 'c', 'd'], dtype="category")
         res = ts.shift(1, fill_value='a')
-        tm.assert_equal(np.array(list(res.values)), np.array([ts.values[0]]+list(ts.values[:-1])))
+        tm.assert_equal(np.array(list(res.values)),
+                        np.array([ts.values[0]] + list(ts.values[:-1])))
 
         with pytest.raises(ValueError):
             ts.shift(1, fill_value='f')

From fa808a40069c9561de70ba00f633143f018dc7b2 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Thu, 13 Dec 2018 02:07:22 +0200
Subject: [PATCH 070/108] !U add specification comment

---
 pandas/tests/series/test_timeseries.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/pandas/tests/series/test_timeseries.py b/pandas/tests/series/test_timeseries.py
index c571524836d8a..3274c8b2a7302 100644
--- a/pandas/tests/series/test_timeseries.py
+++ b/pandas/tests/series/test_timeseries.py
@@ -157,6 +157,7 @@ def test_categorical_shift_fill_value(self):
         tm.assert_equal(np.array(list(res.values)),
                         np.array([ts.values[0]] + list(ts.values[:-1])))
 
+        # check for incorrect fill_value
         with pytest.raises(ValueError):
             ts.shift(1, fill_value='f')
 

From 71b8df18b8142b88f8fc22ce2d088b853e8085f5 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Thu, 13 Dec 2018 15:31:14 +0200
Subject: [PATCH 071/108] !U change test for categorical

---
 pandas/tests/series/test_timeseries.py | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/pandas/tests/series/test_timeseries.py b/pandas/tests/series/test_timeseries.py
index 3274c8b2a7302..379c8b1b69b48 100644
--- a/pandas/tests/series/test_timeseries.py
+++ b/pandas/tests/series/test_timeseries.py
@@ -154,8 +154,10 @@ def test_shift_fill_value(self):
     def test_categorical_shift_fill_value(self):
         ts = pd.Series(['a', 'b', 'c', 'd'], dtype="category")
         res = ts.shift(1, fill_value='a')
-        tm.assert_equal(np.array(list(res.values)),
-                        np.array([ts.values[0]] + list(ts.values[:-1])))
+        expected = pd.Series(pd.Categorical(['a', 'a', 'b', 'c'],
+                                            categories=['a', 'b', 'c', 'd'],
+                                            ordered=False))
+        tm.assert_equal(res, expected)
 
         # check for incorrect fill_value
         with pytest.raises(ValueError):

From 31a844ea076c1e391b600dce5e18153ed2647d3b Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Thu, 13 Dec 2018 15:35:50 +0200
Subject: [PATCH 072/108] !U add check for different parameters

---
 pandas/tests/arrays/sparse/test_array.py | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/pandas/tests/arrays/sparse/test_array.py b/pandas/tests/arrays/sparse/test_array.py
index 45dcf55d4bf23..6757351e6e5ee 100644
--- a/pandas/tests/arrays/sparse/test_array.py
+++ b/pandas/tests/arrays/sparse/test_array.py
@@ -264,10 +264,12 @@ def test_take_negative(self):
 
     def test_shift_fill_value(self):
         # GH #24128
-        sparse = SparseArray(np.array([1, 0, 0, 3, 0]))
-        res = sparse.shift(1, fill_value=0)
-        exp = SparseArray(np.array([0, 1, 0, 0, 3]))
-        tm.assert_sp_array_equal(res, exp)
+        fill_values = [0, None, np.nan]
+        for fill_value in fill_values:
+            sparse = SparseArray(np.array([1, 0, 0, 3, 0]))
+            res = sparse.shift(1, fill_value=fill_value)
+            exp = SparseArray(np.array([fill_value, 1, 0, 0, 3]))
+            tm.assert_sp_array_equal(res, exp)
 
     def test_bad_take(self):
         with pytest.raises(IndexError, match="bounds"):

From 18cbd955782a473ebfa89350e73849a506551116 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Thu, 13 Dec 2018 15:37:50 +0200
Subject: [PATCH 073/108] !U move the check to the top

---
 pandas/core/arrays/sparse.py | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/pandas/core/arrays/sparse.py b/pandas/core/arrays/sparse.py
index ac8ec1596947e..8728097e50506 100644
--- a/pandas/core/arrays/sparse.py
+++ b/pandas/core/arrays/sparse.py
@@ -894,6 +894,7 @@ def shift(self, periods=1, fill_value=None):
 
         if fill_value is None:
             res_type = np.nan
+            fill_value = self.dtype.na_value
         else:
             res_type = fill_value
 
@@ -905,9 +906,6 @@ def shift(self, periods=1, fill_value=None):
         else:
             arr = self
 
-        if fill_value is None:
-            fill_value = self.dtype.na_value
-
         empty = self._from_sequence(
             [fill_value] * min(abs(periods), len(self)),
             dtype=arr.dtype

From d0681505ae06230ca530d4ac20ca53eaf321f844 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Thu, 13 Dec 2018 15:38:52 +0200
Subject: [PATCH 074/108] !U remove index test

---
 pandas/tests/series/test_timeseries.py | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/pandas/tests/series/test_timeseries.py b/pandas/tests/series/test_timeseries.py
index 379c8b1b69b48..1231225f68760 100644
--- a/pandas/tests/series/test_timeseries.py
+++ b/pandas/tests/series/test_timeseries.py
@@ -134,12 +134,6 @@ def test_shift_fill_value(self):
         ts = Series([1.0, 2.0, 3.0, 4.0, 5.0],
                     index=date_range('1/1/2000', periods=5, freq='H'))
 
-        # fill_value should have no effect on shift with freq
-        result = ts.shift(1, freq='5T', fill_value=0)
-        exp_index = ts.index.shift(1, freq='5T')
-        tm.assert_index_equal(result.index, exp_index)
-        tm.assert_numpy_array_equal(result.values, ts.values)
-
         exp = Series([0.0, 1.0, 2.0, 3.0, 4.0],
                      index=date_range('1/1/2000', periods=5, freq='H'))
         # check that fill value works

From e665f7d6fc478586b7dd7132f471d962df8f2f6a Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Fri, 14 Dec 2018 02:00:01 +0200
Subject: [PATCH 075/108] !U remove the None from the list

---
 pandas/tests/arrays/sparse/test_array.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pandas/tests/arrays/sparse/test_array.py b/pandas/tests/arrays/sparse/test_array.py
index 6757351e6e5ee..ef3e3fb9e45d9 100644
--- a/pandas/tests/arrays/sparse/test_array.py
+++ b/pandas/tests/arrays/sparse/test_array.py
@@ -264,7 +264,7 @@ def test_take_negative(self):
 
     def test_shift_fill_value(self):
         # GH #24128
-        fill_values = [0, None, np.nan]
+        fill_values = [0, np.nan]
         for fill_value in fill_values:
             sparse = SparseArray(np.array([1, 0, 0, 3, 0]))
             res = sparse.shift(1, fill_value=fill_value)

From c5a95cb39b6e6db8b509ec7710cb5e247351102a Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Fri, 14 Dec 2018 03:14:38 +0200
Subject: [PATCH 076/108] !U change the sparse ArrayTest

---
 pandas/tests/arrays/sparse/test_array.py | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/pandas/tests/arrays/sparse/test_array.py b/pandas/tests/arrays/sparse/test_array.py
index ef3e3fb9e45d9..44eb9f6866e06 100644
--- a/pandas/tests/arrays/sparse/test_array.py
+++ b/pandas/tests/arrays/sparse/test_array.py
@@ -264,11 +264,16 @@ def test_take_negative(self):
 
     def test_shift_fill_value(self):
         # GH #24128
-        fill_values = [0, np.nan]
+        fill_values = [0, None, np.nan]
         for fill_value in fill_values:
-            sparse = SparseArray(np.array([1, 0, 0, 3, 0]))
+            print(fill_value)
+            sparse = SparseArray(np.array([1, 0, 0, 3, 0]),
+                                 fill_value=8.0)
             res = sparse.shift(1, fill_value=fill_value)
-            exp = SparseArray(np.array([fill_value, 1, 0, 0, 3]))
+            if fill_value is None:
+                fill_value = res.dtype.na_value
+            exp = SparseArray(np.array([fill_value, 1, 0, 0, 3]),
+                              fill_value=8.0)
             tm.assert_sp_array_equal(res, exp)
 
     def test_bad_take(self):

From b03a3fdaa7eade29c3df32f944fd757353631c6d Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Tue, 18 Dec 2018 00:37:22 +0200
Subject: [PATCH 077/108] change the way for parametrizing a test

---
 pandas/tests/arrays/sparse/test_array.py | 24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/pandas/tests/arrays/sparse/test_array.py b/pandas/tests/arrays/sparse/test_array.py
index 44eb9f6866e06..80f715c6ac86e 100644
--- a/pandas/tests/arrays/sparse/test_array.py
+++ b/pandas/tests/arrays/sparse/test_array.py
@@ -262,19 +262,19 @@ def test_take_negative(self):
         exp = SparseArray(np.take(self.arr_data, [-4, -3, -2]))
         tm.assert_sp_array_equal(self.arr.take([-4, -3, -2]), exp)
 
-    def test_shift_fill_value(self):
+    @pytest.mark.parametrize('fill_value', [
+        [0, None, np.nan]
+    ])
+    def test_shift_fill_value(self, fill_value):
         # GH #24128
-        fill_values = [0, None, np.nan]
-        for fill_value in fill_values:
-            print(fill_value)
-            sparse = SparseArray(np.array([1, 0, 0, 3, 0]),
-                                 fill_value=8.0)
-            res = sparse.shift(1, fill_value=fill_value)
-            if fill_value is None:
-                fill_value = res.dtype.na_value
-            exp = SparseArray(np.array([fill_value, 1, 0, 0, 3]),
-                              fill_value=8.0)
-            tm.assert_sp_array_equal(res, exp)
+        sparse = SparseArray(np.array([1, 0, 0, 3, 0]),
+                             fill_value=8.0)
+        res = sparse.shift(1, fill_value=fill_value)
+        if fill_value is None:
+            fill_value = res.dtype.na_value
+        exp = SparseArray(np.array([fill_value, 1, 0, 0, 3]),
+                          fill_value=8.0)
+        tm.assert_sp_array_equal(res, exp)
 
     def test_bad_take(self):
         with pytest.raises(IndexError, match="bounds"):

From d9efb459bcb1be5ab5171ed310f497c3c654b855 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Tue, 18 Dec 2018 00:40:04 +0200
Subject: [PATCH 078/108] update the doc

---
 pandas/core/generic.py | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/pandas/core/generic.py b/pandas/core/generic.py
index 13e71c566511b..789f40c042519 100644
--- a/pandas/core/generic.py
+++ b/pandas/core/generic.py
@@ -8840,9 +8840,11 @@ def mask(self, cond, other=np.nan, inplace=False, axis=None, level=None,
         axis : {0 or 'index', 1 or 'columns', None}, default None
             Shift direction.
         fill_value : object, optional
-            the scalar value to use for newly introduced missing values.
-            the default depends on the dtype of `self`. for numeric data,
-            ``np.nan`` is used. for datelike, ``pandas.nat`` is used.
+            The scalar value to use for newly introduced missing values.
+            the default depends on the dtype of `self`. For numeric data,
+            ``np.nan`` is used. 
+            For datetime, timedelta, or period data, etc. :attr:`NaT` is used.
+            For extension dtypes, self.dtype.na_value is used.
 
             .. versionchanged:: 0.24.0
 

From 60595c90e828dd90edda226b5baa9732de86fa51 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Tue, 18 Dec 2018 00:40:22 +0200
Subject: [PATCH 079/108] update doc

---
 pandas/core/generic.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/pandas/core/generic.py b/pandas/core/generic.py
index 789f40c042519..42aba4794cf26 100644
--- a/pandas/core/generic.py
+++ b/pandas/core/generic.py
@@ -8841,8 +8841,8 @@ def mask(self, cond, other=np.nan, inplace=False, axis=None, level=None,
             Shift direction.
         fill_value : object, optional
             The scalar value to use for newly introduced missing values.
-            the default depends on the dtype of `self`. For numeric data,
-            ``np.nan`` is used. 
+            the default depends on the dtype of `self`. 
+            For numeric data, ``np.nan`` is used. 
             For datetime, timedelta, or period data, etc. :attr:`NaT` is used.
             For extension dtypes, self.dtype.na_value is used.
 

From 7fc9900f6a3e12537bc6ab805d9499bed479b3a6 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Tue, 18 Dec 2018 00:46:24 +0200
Subject: [PATCH 080/108] add a test for dtype

---
 pandas/tests/series/test_timeseries.py | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/pandas/tests/series/test_timeseries.py b/pandas/tests/series/test_timeseries.py
index 1231225f68760..5bc5a648c404f 100644
--- a/pandas/tests/series/test_timeseries.py
+++ b/pandas/tests/series/test_timeseries.py
@@ -145,6 +145,10 @@ def test_shift_fill_value(self):
         result = ts.shift(2, fill_value=0.0)
         tm.assert_series_equal(result, exp)
 
+        ts = pd.Series([1, 2, 3])
+        res = ts.shift(2, fill_value=0)
+        assert res.dtype == ts.dtype
+
     def test_categorical_shift_fill_value(self):
         ts = pd.Series(['a', 'b', 'c', 'd'], dtype="category")
         res = ts.shift(1, fill_value='a')

From e1a83e2c53c3629bae666ba4a070b5c849fb9429 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Tue, 18 Dec 2018 01:25:33 +0200
Subject: [PATCH 081/108] fix the parametrize arguments

---
 pandas/tests/arrays/sparse/test_array.py | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/pandas/tests/arrays/sparse/test_array.py b/pandas/tests/arrays/sparse/test_array.py
index 80f715c6ac86e..122b41ea1fa4c 100644
--- a/pandas/tests/arrays/sparse/test_array.py
+++ b/pandas/tests/arrays/sparse/test_array.py
@@ -262,9 +262,7 @@ def test_take_negative(self):
         exp = SparseArray(np.take(self.arr_data, [-4, -3, -2]))
         tm.assert_sp_array_equal(self.arr.take([-4, -3, -2]), exp)
 
-    @pytest.mark.parametrize('fill_value', [
-        [0, None, np.nan]
-    ])
+    @pytest.mark.parametrize('fill_value', [0, None, np.nan])
     def test_shift_fill_value(self, fill_value):
         # GH #24128
         sparse = SparseArray(np.array([1, 0, 0, 3, 0]),

From 7b587c2322238e0eb38cfb3c04dd769719dd432b Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Tue, 18 Dec 2018 02:05:25 +0200
Subject: [PATCH 082/108] !U change the doc formatting

---
 pandas/core/generic.py | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/pandas/core/generic.py b/pandas/core/generic.py
index 42aba4794cf26..58cdbc34d2837 100644
--- a/pandas/core/generic.py
+++ b/pandas/core/generic.py
@@ -8841,10 +8841,10 @@ def mask(self, cond, other=np.nan, inplace=False, axis=None, level=None,
             Shift direction.
         fill_value : object, optional
             The scalar value to use for newly introduced missing values.
-            the default depends on the dtype of `self`. 
-            For numeric data, ``np.nan`` is used. 
-            For datetime, timedelta, or period data, etc. :attr:`NaT` is used.
-            For extension dtypes, self.dtype.na_value is used.
+            the default depends on the dtype of `self`. For numeric data, 
+            ``np.nan`` is used. For datetime, timedelta, or period data, etc. 
+            :attr:`NaT` is used. For extension dtypes, self.dtype.na_value 
+            is used.
 
             .. versionchanged:: 0.24.0
 

From 7bf6768293f3dbac34dee690e81be697dce6a927 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Tue, 18 Dec 2018 22:27:03 +0200
Subject: [PATCH 083/108] !U remove the trailing whitespaces

---
 pandas/core/generic.py | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/pandas/core/generic.py b/pandas/core/generic.py
index 58cdbc34d2837..ff80393fbb6d7 100644
--- a/pandas/core/generic.py
+++ b/pandas/core/generic.py
@@ -8841,10 +8841,10 @@ def mask(self, cond, other=np.nan, inplace=False, axis=None, level=None,
             Shift direction.
         fill_value : object, optional
             The scalar value to use for newly introduced missing values.
-            the default depends on the dtype of `self`. For numeric data, 
-            ``np.nan`` is used. For datetime, timedelta, or period data, etc. 
-            :attr:`NaT` is used. For extension dtypes, self.dtype.na_value 
-            is used.
+            the default depends on the dtype of `self`.
+            For numeric data, ``np.nan`` is used.
+            For datetime, timedelta, or period data, etc. :attr:`NaT` is used.
+            For extension dtypes, self.dtype.na_value is used.
 
             .. versionchanged:: 0.24.0
 

From 09f0fdedb6b9bdec8cd8c6c231ea46fd5c9d15dd Mon Sep 17 00:00:00 2001
From: Tom Augspurger <TomAugspurger@users.noreply.github.com>
Date: Wed, 19 Dec 2018 00:17:38 +0200
Subject: [PATCH 084/108] Update pandas/core/generic.py

Co-Authored-By: ahcub <olex.buchkovsky@gmail.com>
---
 pandas/core/generic.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pandas/core/generic.py b/pandas/core/generic.py
index ff80393fbb6d7..8022456a0e575 100644
--- a/pandas/core/generic.py
+++ b/pandas/core/generic.py
@@ -8844,7 +8844,7 @@ def mask(self, cond, other=np.nan, inplace=False, axis=None, level=None,
             the default depends on the dtype of `self`.
             For numeric data, ``np.nan`` is used.
             For datetime, timedelta, or period data, etc. :attr:`NaT` is used.
-            For extension dtypes, self.dtype.na_value is used.
+            For extension dtypes, ``self.dtype.na_value`` is used.
 
             .. versionchanged:: 0.24.0
 

From 6d65cfa633107f3507d1b3186a955a6130583bc0 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Wed, 19 Dec 2018 00:21:14 +0200
Subject: [PATCH 085/108] !U try to remove res_type

---
 pandas/core/arrays/sparse.py | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/pandas/core/arrays/sparse.py b/pandas/core/arrays/sparse.py
index 8728097e50506..6cedf6c1b0ae3 100644
--- a/pandas/core/arrays/sparse.py
+++ b/pandas/core/arrays/sparse.py
@@ -893,12 +893,9 @@ def shift(self, periods=1, fill_value=None):
             return self.copy()
 
         if fill_value is None:
-            res_type = np.nan
             fill_value = self.dtype.na_value
-        else:
-            res_type = fill_value
 
-        subtype = np.result_type(res_type, self.dtype.subtype)
+        subtype = np.result_type(fill_value, self.dtype.subtype)
 
         if subtype != self.dtype.subtype:
             # just coerce up front

From 3f9b62bbf0bd979328f3e5ba93df301ba9ff8fce Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Wed, 19 Dec 2018 00:34:04 +0200
Subject: [PATCH 086/108] !U add test for categorical shift with fill value as
 nan

---
 pandas/tests/groupby/test_categorical.py | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/pandas/tests/groupby/test_categorical.py b/pandas/tests/groupby/test_categorical.py
index f0d0ac246a251..e69b6087b849e 100644
--- a/pandas/tests/groupby/test_categorical.py
+++ b/pandas/tests/groupby/test_categorical.py
@@ -9,7 +9,8 @@
 from pandas.compat import PY37
 from pandas import (Index, MultiIndex, CategoricalIndex,
                     DataFrame, Categorical, Series, qcut)
-from pandas.util.testing import assert_frame_equal, assert_series_equal
+from pandas.util.testing import (assert_equal,
+                                 assert_frame_equal, assert_series_equal)
 import pandas.util.testing as tm
 
 
@@ -861,3 +862,16 @@ def test_groupby_multiindex_categorical_datetime():
     expected = pd.DataFrame(
         {'values': [0, 4, 8, 3, 4, 5, 6, np.nan, 2]}, index=idx)
     assert_frame_equal(result, expected)
+
+
+def test_shift():
+    ct = pd.Categorical(['a', 'b', 'c', 'd'],
+                        categories=['a', 'b', 'c', 'd'], ordered=False)
+    expected = pd.Categorical([None, 'a', 'b', 'c'],
+                              categories=['a', 'b', 'c', 'd'], ordered=False)
+    res = ct.shift(1)
+    assert_equal(res, expected)
+    res = ct.shift(1, fill_value=None)
+    assert_equal(res, expected)
+    res = ct.shift(1, fill_value=np.nan)
+    assert_equal(res, expected)

From 8fa8a15668d47560e0051e3fe4e9d6a06043f52c Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Wed, 19 Dec 2018 00:34:55 +0200
Subject: [PATCH 087/108] add different variation of nan

---
 pandas/tests/groupby/test_categorical.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/pandas/tests/groupby/test_categorical.py b/pandas/tests/groupby/test_categorical.py
index e69b6087b849e..31ed95c640587 100644
--- a/pandas/tests/groupby/test_categorical.py
+++ b/pandas/tests/groupby/test_categorical.py
@@ -871,7 +871,7 @@ def test_shift():
                               categories=['a', 'b', 'c', 'd'], ordered=False)
     res = ct.shift(1)
     assert_equal(res, expected)
-    res = ct.shift(1, fill_value=None)
-    assert_equal(res, expected)
     res = ct.shift(1, fill_value=np.nan)
     assert_equal(res, expected)
+    res = ct.shift(1, fill_value=pd.NaT)
+    assert_equal(res, expected)

From 6c9610839c6e41e534454acb59d8c3959371b4b6 Mon Sep 17 00:00:00 2001
From: Tom Augspurger <tom.w.augspurger@gmail.com>
Date: Thu, 20 Dec 2018 16:22:41 -0600
Subject: [PATCH 088/108] added base test

---
 pandas/tests/extension/base/methods.py | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/pandas/tests/extension/base/methods.py b/pandas/tests/extension/base/methods.py
index 4a409a84f3db4..2bcdb8aa7488c 100644
--- a/pandas/tests/extension/base/methods.py
+++ b/pandas/tests/extension/base/methods.py
@@ -221,6 +221,17 @@ def test_shift_empty_array(self, data, periods):
         expected = empty
         self.assert_extension_array_equal(result, expected)
 
+    def test_shift_fill_value(self, data):
+        arr = data[:4]
+        fill_value = data[0]
+        result = arr.shift(1, fill_value=fill_value)
+        expected = data.take([0, 0, 1, 2])
+        self.assert_extension_array_equal(result, expected)
+
+        result = arr.shift(-2, fill_value=fill_value)
+        expected = data.take([2, 3, 0, 0])
+        self.assert_extension_array_equal(result, expected)
+
     @pytest.mark.parametrize("as_frame", [True, False])
     def test_hash_pandas_object_works(self, data, as_frame):
         # https://github.com/pandas-dev/pandas/issues/23066

From eb48cfe3ff6038f6ce35e0600f972721337bded2 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Tue, 25 Dec 2018 20:02:33 +0200
Subject: [PATCH 089/108] change the fill_value so the result data set stays
 int

---
 pandas/core/generic.py | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/pandas/core/generic.py b/pandas/core/generic.py
index 8022456a0e575..949af2f874fdf 100644
--- a/pandas/core/generic.py
+++ b/pandas/core/generic.py
@@ -8883,13 +8883,13 @@ def mask(self, cond, other=np.nan, inplace=False, axis=None, level=None,
         3   NaN  30.0  33.0
         4   NaN  45.0  48.0
 
-        >>> df.shift(periods=3, fill_value=0.0)
+        >>> df.shift(periods=3, fill_value=0)
            Col1  Col2  Col3
-        0   0.0   0.0   0.0
-        1   0.0   0.0   0.0
-        2   0.0   0.0   0.0
-        3  10.0  13.0  17.0
-        4  20.0  23.0  27.0
+        0     0     0     0
+        1     0     0     0
+        2     0     0     0
+        3    10    13    17
+        4    20    23    27
     """)
 
     @Appender(_shared_docs['shift'] % _shared_doc_kwargs)

From a72cffe30e2903b04cbc8d0285c959fb7698fa2e Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Tue, 25 Dec 2018 20:03:29 +0200
Subject: [PATCH 090/108] add a blank line before the version tag

---
 pandas/core/arrays/period.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/pandas/core/arrays/period.py b/pandas/core/arrays/period.py
index 93ccceba20c6c..a90b9377ff66e 100644
--- a/pandas/core/arrays/period.py
+++ b/pandas/core/arrays/period.py
@@ -472,6 +472,7 @@ def shift(self, periods=1, fill_value=None):
             The number of periods to shift. Negative values are allowed
             for shifting backwards.
         fill_value : optional, default NaT
+
             .. versionadded:: 0.24.0
 
         Returns

From 25b466116212b6c259d4b009cd05103b00398c14 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Tue, 25 Dec 2018 20:03:59 +0200
Subject: [PATCH 091/108] add a blank line before the version tag

---
 pandas/core/groupby/groupby.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/pandas/core/groupby/groupby.py b/pandas/core/groupby/groupby.py
index 3a158d394d375..5658d7a541e27 100644
--- a/pandas/core/groupby/groupby.py
+++ b/pandas/core/groupby/groupby.py
@@ -2003,6 +2003,7 @@ def shift(self, periods=1, freq=None, axis=0, fill_value=None):
         freq : frequency string
         axis : axis to shift, default 0
         fill_value : optional
+
             .. versionadded:: 0.24.0
         """
 

From 0afad10d0ecfab82e28d8a397720a64e2bd8c888 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Tue, 25 Dec 2018 20:05:31 +0200
Subject: [PATCH 092/108] change the fill_value check for na

---
 pandas/core/internals/blocks.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pandas/core/internals/blocks.py b/pandas/core/internals/blocks.py
index be075b19fef5f..0ccfab93c2830 100644
--- a/pandas/core/internals/blocks.py
+++ b/pandas/core/internals/blocks.py
@@ -3040,7 +3040,7 @@ def shift(self, periods, axis=0, fill_value=None):
 
         new_values = self.values.asi8.take(indexer)
 
-        if fill_value is None:
+        if isna(fill_value):
             fill_value = tslibs.iNaT
         if periods > 0:
             new_values[:periods] = fill_value

From bb679059366160e1721da2d4c6295a3bcec22b4b Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Tue, 25 Dec 2018 20:10:49 +0200
Subject: [PATCH 093/108] parametrize on fill value with decorator instead of
 the test internals

---
 pandas/tests/groupby/test_categorical.py | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/pandas/tests/groupby/test_categorical.py b/pandas/tests/groupby/test_categorical.py
index 26ef442ed10ad..7eda113be0e36 100644
--- a/pandas/tests/groupby/test_categorical.py
+++ b/pandas/tests/groupby/test_categorical.py
@@ -863,14 +863,11 @@ def test_groupby_multiindex_categorical_datetime():
     assert_frame_equal(result, expected)
 
 
-def test_shift():
+@pytest.mark.parametrize('fill_value', [None, np.nan, pd.NaT])
+def test_shift(fill_value):
     ct = pd.Categorical(['a', 'b', 'c', 'd'],
                         categories=['a', 'b', 'c', 'd'], ordered=False)
     expected = pd.Categorical([None, 'a', 'b', 'c'],
                               categories=['a', 'b', 'c', 'd'], ordered=False)
-    res = ct.shift(1)
-    assert_equal(res, expected)
-    res = ct.shift(1, fill_value=np.nan)
-    assert_equal(res, expected)
-    res = ct.shift(1, fill_value=pd.NaT)
+    res = ct.shift(1, fill_value=fill_value)
     assert_equal(res, expected)

From f5aad59ef0149b2f3e26489c86275397cf6319d7 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Tue, 25 Dec 2018 20:12:50 +0200
Subject: [PATCH 094/108] change check for is None to isna

---
 pandas/core/arrays/base.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/pandas/core/arrays/base.py b/pandas/core/arrays/base.py
index b4e413f16247e..eab3cfc86e7a8 100644
--- a/pandas/core/arrays/base.py
+++ b/pandas/core/arrays/base.py
@@ -9,6 +9,7 @@
 
 import numpy as np
 
+from pandas.core.dtypes.missing import isna
 from pandas.compat import PY3, set_function_name
 from pandas.compat.numpy import function as nv
 from pandas.errors import AbstractMethodError
@@ -486,7 +487,7 @@ def shift(self, periods=1, fill_value=None):
         if not len(self) or periods == 0:
             return self.copy()
 
-        if fill_value is None:
+        if isna(fill_value):
             fill_value = self.dtype.na_value
 
         empty = self._from_sequence(

From 025f0db8a5a073bf571082bdc6dfa3e984115bab Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Tue, 25 Dec 2018 20:14:20 +0200
Subject: [PATCH 095/108] change check for is None to isna

---
 pandas/tests/arrays/sparse/test_array.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/pandas/tests/arrays/sparse/test_array.py b/pandas/tests/arrays/sparse/test_array.py
index 81876e73c80cc..3ccffa3cf7902 100644
--- a/pandas/tests/arrays/sparse/test_array.py
+++ b/pandas/tests/arrays/sparse/test_array.py
@@ -5,6 +5,7 @@
 import numpy as np
 import pytest
 
+from pandas.core.dtypes.missing import isna
 from pandas._libs.sparse import IntIndex
 from pandas.compat import range
 import pandas.util._test_decorators as td
@@ -268,7 +269,7 @@ def test_shift_fill_value(self, fill_value):
         sparse = SparseArray(np.array([1, 0, 0, 3, 0]),
                              fill_value=8.0)
         res = sparse.shift(1, fill_value=fill_value)
-        if fill_value is None:
+        if isna(fill_value):
             fill_value = res.dtype.na_value
         exp = SparseArray(np.array([fill_value, 1, 0, 0, 3]),
                           fill_value=8.0)

From 8ce460af74da21b1832ce448fc5860d015cea718 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Tue, 25 Dec 2018 20:14:26 +0200
Subject: [PATCH 096/108] change check for is None to isna

---
 pandas/core/arrays/sparse.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pandas/core/arrays/sparse.py b/pandas/core/arrays/sparse.py
index 15b809f8fd92a..e4a8c21bbb839 100644
--- a/pandas/core/arrays/sparse.py
+++ b/pandas/core/arrays/sparse.py
@@ -894,7 +894,7 @@ def shift(self, periods=1, fill_value=None):
         if not len(self) or periods == 0:
             return self.copy()
 
-        if fill_value is None:
+        if isna(fill_value):
             fill_value = self.dtype.na_value
 
         subtype = np.result_type(fill_value, self.dtype.subtype)

From dce5aa1799e0080d85e4265490a315831ec4f70a Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Tue, 25 Dec 2018 20:15:20 +0200
Subject: [PATCH 097/108] change check for is None to isna

---
 pandas/core/groupby/groupby.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pandas/core/groupby/groupby.py b/pandas/core/groupby/groupby.py
index fc01c8a1bd313..60b6c843492c7 100644
--- a/pandas/core/groupby/groupby.py
+++ b/pandas/core/groupby/groupby.py
@@ -2009,7 +2009,7 @@ def shift(self, periods=1, freq=None, axis=0, fill_value=None):
             .. versionadded:: 0.24.0
         """
 
-        if freq is not None or axis != 0 or fill_value is not None:
+        if freq is not None or axis != 0 or not isna(fill_value):
             return self.apply(lambda x: x.shift(periods, freq,
                                                 axis, fill_value))
 

From d60632addbb2906cf4895ae255ea51f2f21276f8 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Tue, 25 Dec 2018 22:05:11 +0200
Subject: [PATCH 098/108] fix imports sorting

---
 pandas/tests/arrays/sparse/test_array.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pandas/tests/arrays/sparse/test_array.py b/pandas/tests/arrays/sparse/test_array.py
index 3ccffa3cf7902..9340f35eaa019 100644
--- a/pandas/tests/arrays/sparse/test_array.py
+++ b/pandas/tests/arrays/sparse/test_array.py
@@ -5,13 +5,13 @@
 import numpy as np
 import pytest
 
-from pandas.core.dtypes.missing import isna
 from pandas._libs.sparse import IntIndex
 from pandas.compat import range
 import pandas.util._test_decorators as td
 
 import pandas as pd
 from pandas.core.sparse.api import SparseArray, SparseDtype, SparseSeries
+from pandas.core.dtypes.missing import isna
 import pandas.util.testing as tm
 from pandas.util.testing import assert_almost_equal
 

From a0ab35dab62006a0dc6b8b7aa009107691a908c6 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Tue, 25 Dec 2018 22:05:23 +0200
Subject: [PATCH 099/108] fix imports sorting

---
 pandas/core/arrays/base.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pandas/core/arrays/base.py b/pandas/core/arrays/base.py
index eab3cfc86e7a8..06303e6bb0498 100644
--- a/pandas/core/arrays/base.py
+++ b/pandas/core/arrays/base.py
@@ -9,12 +9,12 @@
 
 import numpy as np
 
-from pandas.core.dtypes.missing import isna
 from pandas.compat import PY3, set_function_name
 from pandas.compat.numpy import function as nv
 from pandas.errors import AbstractMethodError
 
 from pandas.core.dtypes.common import is_list_like
+from pandas.core.dtypes.missing import isna
 from pandas.core.dtypes.generic import ABCIndexClass, ABCSeries
 
 from pandas.core import ops

From fd23842a0e8b07a05ecc3525931a7019487a9a8c Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Tue, 25 Dec 2018 22:20:08 +0200
Subject: [PATCH 100/108] fix imports sorting

---
 pandas/core/arrays/base.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pandas/core/arrays/base.py b/pandas/core/arrays/base.py
index 06303e6bb0498..262f043e1f0a1 100644
--- a/pandas/core/arrays/base.py
+++ b/pandas/core/arrays/base.py
@@ -14,8 +14,8 @@
 from pandas.errors import AbstractMethodError
 
 from pandas.core.dtypes.common import is_list_like
-from pandas.core.dtypes.missing import isna
 from pandas.core.dtypes.generic import ABCIndexClass, ABCSeries
+from pandas.core.dtypes.missing import isna
 
 from pandas.core import ops
 

From 3503e86f4baeaf5134e6474e6d62818bc9f04fad Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Tue, 25 Dec 2018 22:20:51 +0200
Subject: [PATCH 101/108] fix imports sorting

---
 pandas/tests/arrays/sparse/test_array.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/pandas/tests/arrays/sparse/test_array.py b/pandas/tests/arrays/sparse/test_array.py
index 9340f35eaa019..5d7f9ec69a573 100644
--- a/pandas/tests/arrays/sparse/test_array.py
+++ b/pandas/tests/arrays/sparse/test_array.py
@@ -9,9 +9,10 @@
 from pandas.compat import range
 import pandas.util._test_decorators as td
 
+from pandas.core.dtypes.missing import isna
+
 import pandas as pd
 from pandas.core.sparse.api import SparseArray, SparseDtype, SparseSeries
-from pandas.core.dtypes.missing import isna
 import pandas.util.testing as tm
 from pandas.util.testing import assert_almost_equal
 

From 674f15db95f4bc5fd63a00e4746c97fc2de5839b Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Tue, 25 Dec 2018 23:18:19 +0200
Subject: [PATCH 102/108] Add the whatsnew entry

---
 doc/source/whatsnew/v0.24.0.rst | 1 +
 1 file changed, 1 insertion(+)

diff --git a/doc/source/whatsnew/v0.24.0.rst b/doc/source/whatsnew/v0.24.0.rst
index 1fb43de5f4c5a..613f9eeb6e8e4 100644
--- a/doc/source/whatsnew/v0.24.0.rst
+++ b/doc/source/whatsnew/v0.24.0.rst
@@ -31,6 +31,7 @@ New features
 - :func:`read_feather` now accepts ``columns`` as an argument, allowing the user to specify which columns should be read. (:issue:`24025`)
 - :func:`DataFrame.to_html` now accepts ``render_links`` as an argument, allowing the user to generate HTML with links to any URLs that appear in the DataFrame.
   See the :ref:`section on writing HTML <io.html>` in the IO docs for example usage. (:issue:`2679`)
+- :func:`shift` method for DataFrame, Series, ExtensionArray, SparseArray, Period, GroupBy, NDFrame, Block now accepts fill_value as an argument, allowing the user to specify a value which will be used instead of NA/NaT in the empty periods
 
 .. _whatsnew_0240.values_api:
 

From 3c896ab110dc78d2156924ea1b2f607e94395fd5 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Tue, 25 Dec 2018 23:21:47 +0200
Subject: [PATCH 103/108] change func to meth

---
 doc/source/whatsnew/v0.24.0.rst | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/doc/source/whatsnew/v0.24.0.rst b/doc/source/whatsnew/v0.24.0.rst
index 613f9eeb6e8e4..904814c956c89 100644
--- a/doc/source/whatsnew/v0.24.0.rst
+++ b/doc/source/whatsnew/v0.24.0.rst
@@ -31,7 +31,7 @@ New features
 - :func:`read_feather` now accepts ``columns`` as an argument, allowing the user to specify which columns should be read. (:issue:`24025`)
 - :func:`DataFrame.to_html` now accepts ``render_links`` as an argument, allowing the user to generate HTML with links to any URLs that appear in the DataFrame.
   See the :ref:`section on writing HTML <io.html>` in the IO docs for example usage. (:issue:`2679`)
-- :func:`shift` method for DataFrame, Series, ExtensionArray, SparseArray, Period, GroupBy, NDFrame, Block now accepts fill_value as an argument, allowing the user to specify a value which will be used instead of NA/NaT in the empty periods
+- :meth:`shift` method for DataFrame, Series, ExtensionArray, SparseArray, Period, GroupBy, NDFrame, Block now accepts fill_value as an argument, allowing the user to specify a value which will be used instead of NA/NaT in the empty periods
 
 .. _whatsnew_0240.values_api:
 

From b9d335aedb435babcbea27e0318c9528786f4163 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Tue, 25 Dec 2018 23:24:02 +0200
Subject: [PATCH 104/108] change the description in whatsnew

---
 doc/source/whatsnew/v0.24.0.rst | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/doc/source/whatsnew/v0.24.0.rst b/doc/source/whatsnew/v0.24.0.rst
index 904814c956c89..72879f495ca76 100644
--- a/doc/source/whatsnew/v0.24.0.rst
+++ b/doc/source/whatsnew/v0.24.0.rst
@@ -31,7 +31,7 @@ New features
 - :func:`read_feather` now accepts ``columns`` as an argument, allowing the user to specify which columns should be read. (:issue:`24025`)
 - :func:`DataFrame.to_html` now accepts ``render_links`` as an argument, allowing the user to generate HTML with links to any URLs that appear in the DataFrame.
   See the :ref:`section on writing HTML <io.html>` in the IO docs for example usage. (:issue:`2679`)
-- :meth:`shift` method for DataFrame, Series, ExtensionArray, SparseArray, Period, GroupBy, NDFrame, Block now accepts fill_value as an argument, allowing the user to specify a value which will be used instead of NA/NaT in the empty periods
+- :meth:`DataFrame.shift` :meth:`Series.shift`, :meth:`ExtensionArray.shift`, :meth:`SparseArray.shift`, :meth:`Period.shift`, :meth:`GroupBy.shift`, :meth:`NDFrame.shift` and :meth:`Block.shift` now accepts fill_value as an argument, allowing the user to specify a value which will be used instead of NA/NaT in the empty periods
 
 .. _whatsnew_0240.values_api:
 

From 4fcca01ef6b1085712e4c08092de61274d9e67d3 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Tue, 25 Dec 2018 23:24:21 +0200
Subject: [PATCH 105/108] fix typo

---
 doc/source/whatsnew/v0.24.0.rst | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/doc/source/whatsnew/v0.24.0.rst b/doc/source/whatsnew/v0.24.0.rst
index 72879f495ca76..e13b9736a9361 100644
--- a/doc/source/whatsnew/v0.24.0.rst
+++ b/doc/source/whatsnew/v0.24.0.rst
@@ -31,7 +31,7 @@ New features
 - :func:`read_feather` now accepts ``columns`` as an argument, allowing the user to specify which columns should be read. (:issue:`24025`)
 - :func:`DataFrame.to_html` now accepts ``render_links`` as an argument, allowing the user to generate HTML with links to any URLs that appear in the DataFrame.
   See the :ref:`section on writing HTML <io.html>` in the IO docs for example usage. (:issue:`2679`)
-- :meth:`DataFrame.shift` :meth:`Series.shift`, :meth:`ExtensionArray.shift`, :meth:`SparseArray.shift`, :meth:`Period.shift`, :meth:`GroupBy.shift`, :meth:`NDFrame.shift` and :meth:`Block.shift` now accepts fill_value as an argument, allowing the user to specify a value which will be used instead of NA/NaT in the empty periods
+- :meth:`DataFrame.shift` :meth:`Series.shift`, :meth:`ExtensionArray.shift`, :meth:`SparseArray.shift`, :meth:`Period.shift`, :meth:`GroupBy.shift`, :meth:`NDFrame.shift` and :meth:`Block.shift` now accept fill_value as an argument, allowing the user to specify a value which will be used instead of NA/NaT in the empty periods
 
 .. _whatsnew_0240.values_api:
 

From a24f5c825e0c378330adf332085ab361e1b6aab2 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Tue, 25 Dec 2018 23:25:00 +0200
Subject: [PATCH 106/108] Add categorical to the description

---
 doc/source/whatsnew/v0.24.0.rst | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/doc/source/whatsnew/v0.24.0.rst b/doc/source/whatsnew/v0.24.0.rst
index e13b9736a9361..549dd36d4fbeb 100644
--- a/doc/source/whatsnew/v0.24.0.rst
+++ b/doc/source/whatsnew/v0.24.0.rst
@@ -31,7 +31,7 @@ New features
 - :func:`read_feather` now accepts ``columns`` as an argument, allowing the user to specify which columns should be read. (:issue:`24025`)
 - :func:`DataFrame.to_html` now accepts ``render_links`` as an argument, allowing the user to generate HTML with links to any URLs that appear in the DataFrame.
   See the :ref:`section on writing HTML <io.html>` in the IO docs for example usage. (:issue:`2679`)
-- :meth:`DataFrame.shift` :meth:`Series.shift`, :meth:`ExtensionArray.shift`, :meth:`SparseArray.shift`, :meth:`Period.shift`, :meth:`GroupBy.shift`, :meth:`NDFrame.shift` and :meth:`Block.shift` now accept fill_value as an argument, allowing the user to specify a value which will be used instead of NA/NaT in the empty periods
+- :meth:`DataFrame.shift` :meth:`Series.shift`, :meth:`ExtensionArray.shift`, :meth:`SparseArray.shift`, :meth:`Period.shift`, :meth:`GroupBy.shift`, :meth:`Categorical.shift`, :meth:`NDFrame.shift` and :meth:`Block.shift` now accept fill_value as an argument, allowing the user to specify a value which will be used instead of NA/NaT in the empty periods
 
 .. _whatsnew_0240.values_api:
 

From a92ddfbd0461c0229662a77b98689a5c58a6b600 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Wed, 26 Dec 2018 02:14:43 +0200
Subject: [PATCH 107/108] change import of isna in test

---
 pandas/tests/arrays/sparse/test_array.py | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/pandas/tests/arrays/sparse/test_array.py b/pandas/tests/arrays/sparse/test_array.py
index 5d7f9ec69a573..9c13a20726553 100644
--- a/pandas/tests/arrays/sparse/test_array.py
+++ b/pandas/tests/arrays/sparse/test_array.py
@@ -9,9 +9,8 @@
 from pandas.compat import range
 import pandas.util._test_decorators as td
 
-from pandas.core.dtypes.missing import isna
-
 import pandas as pd
+from pandas import isna
 from pandas.core.sparse.api import SparseArray, SparseDtype, SparseSeries
 import pandas.util.testing as tm
 from pandas.util.testing import assert_almost_equal

From a03cbf5e4afe65c8b6fe8a1eb1eee517d0fc5913 Mon Sep 17 00:00:00 2001
From: Alexander Buchkovsky <olex.buchkovsky@gmail.com>
Date: Wed, 26 Dec 2018 02:16:42 +0200
Subject: [PATCH 108/108] add backticks for fill_value and add the issue number

---
 doc/source/whatsnew/v0.24.0.rst | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/doc/source/whatsnew/v0.24.0.rst b/doc/source/whatsnew/v0.24.0.rst
index 549dd36d4fbeb..2693c98e56582 100644
--- a/doc/source/whatsnew/v0.24.0.rst
+++ b/doc/source/whatsnew/v0.24.0.rst
@@ -31,7 +31,7 @@ New features
 - :func:`read_feather` now accepts ``columns`` as an argument, allowing the user to specify which columns should be read. (:issue:`24025`)
 - :func:`DataFrame.to_html` now accepts ``render_links`` as an argument, allowing the user to generate HTML with links to any URLs that appear in the DataFrame.
   See the :ref:`section on writing HTML <io.html>` in the IO docs for example usage. (:issue:`2679`)
-- :meth:`DataFrame.shift` :meth:`Series.shift`, :meth:`ExtensionArray.shift`, :meth:`SparseArray.shift`, :meth:`Period.shift`, :meth:`GroupBy.shift`, :meth:`Categorical.shift`, :meth:`NDFrame.shift` and :meth:`Block.shift` now accept fill_value as an argument, allowing the user to specify a value which will be used instead of NA/NaT in the empty periods
+- :meth:`DataFrame.shift` :meth:`Series.shift`, :meth:`ExtensionArray.shift`, :meth:`SparseArray.shift`, :meth:`Period.shift`, :meth:`GroupBy.shift`, :meth:`Categorical.shift`, :meth:`NDFrame.shift` and :meth:`Block.shift` now accept `fill_value` as an argument, allowing the user to specify a value which will be used instead of NA/NaT in the empty periods. (:issue:`15486`)
 
 .. _whatsnew_0240.values_api: