added test for size() method

Author: discort

doc/source/whatsnew/v0.19.0.txt

@@ -1562,5 +1562,4 @@ Bug Fixes
 - Bugs in ``stack``, ``get_dummies``, ``make_axis_dummies`` which don't preserve categorical dtypes in (multi)indexes (:issue:`13854`)
 - ``PeriodIndex`` can now accept ``list`` and ``array`` which contains ``pd.NaT`` (:issue:`13430`)
 - Bug in ``df.groupby`` where ``.median()`` returns arbitrary values if grouped dataframe contains empty bins (:issue:`13629`)
-- Bug in ``Index.copy()`` where ``name`` parameter was ignored (:issue:`14302`)
-- Bug in ``_downsample()``. Inconsistent return type on resample of empty DataFrame (:issue:`14962`)
+- Bug in ``Index.copy()`` where ``name`` parameter was ignored (:issue:`14302`)

doc/source/whatsnew/v0.20.0.txt

@@ -457,11 +457,8 @@ Bug Fixes
 - Bug in ``pd.read_csv()`` with ``float_precision='round_trip'`` which caused a segfault when a text entry is parsed (:issue:`15140`)
 
 
+- Bug in ``DataFrame.boxplot`` where ``fontsize`` was not applied to the tick labels on both axes (:issue:`15108`)
 
 
 
-
-
-
-
-- Bug in ``DataFrame.boxplot`` where ``fontsize`` was not applied to the tick labels on both axes (:issue:`15108`)
+- Bug in ``resample().size()``. Inconsistent return type on resample of empty DataFrame (:issue:`14962`)

pandas/tseries/resample.py

@@ -16,6 +16,7 @@
 from pandas.tseries.period import PeriodIndex, period_range
 import pandas.core.common as com
 import pandas.core.algorithms as algos
+from pandas.types.generic import ABCDataFrame
 
 import pandas.compat as compat
 from pandas.compat.numpy import function as nv
@@ -444,6 +445,17 @@ def _wrap_result(self, result):
 
         return result
 
+    def _assure_downsample(self, _method):
+        """Assure that downsample is done with the correct type"""
+        result = self._downsample(_method)
+
+        # Make consistent type of result. GH14962
+        if not len(self.ax) and isinstance(result, ABCDataFrame) and \
+                isinstance(result.index, (DatetimeIndex, TimedeltaIndex)):
+            result = pd.Series([], index=result.index, dtype='int64')
+
+        return result
+
     def pad(self, limit=None):
         """
         Forward fill the values
@@ -567,8 +579,13 @@ def f(self, _method=method, *args, **kwargs):
 # groupby & aggregate methods
 for method in ['count', 'size']:
 
-    def f(self, _method=method):
-        return self._downsample(_method)
+    if method == "size":
+        def f(self, _method=method):
+            return self._assure_downsample(_method)
+    else:
+        def f(self, _method=method):
+            return self._downsample(_method)
+
     f.__doc__ = getattr(GroupBy, method).__doc__
     setattr(Resampler, method, f)
 
@@ -772,14 +789,6 @@ def _wrap_result(self, result):
         if self.kind == 'period' and not isinstance(result.index, PeriodIndex):
             result.index = result.index.to_period(self.freq)
 
-        # Make consistent type of result. GH14962
-        if not len(self.ax):
-            grouper = BinGrouper([], result.index)
-            grouped = self._selected_obj.groupby(grouper)
-            result = pd.Series([],
-                               index=result.index,
-                               name=grouped.name,
-                               dtype='int64')
         return result
 
 

pandas/tseries/tests/test_resample.py

@@ -748,7 +748,7 @@ def test_resample_empty_series(self):
                     assert_series_equal(result, expected, check_dtype=False,
                                         check_names=False)
                     # this assert will break when fixed
-                    # self.assertTrue(result.name is None)
+                    self.assertTrue(result.name is None)
                 else:
                     assert_series_equal(result, expected, check_dtype=False)
 
@@ -759,18 +759,37 @@ def test_resample_empty_dataframe(self):
 
         for freq in ['M', 'D', 'H']:
             # count retains dimensions too
-            methods = downsample_methods + upsample_methods
+            methods = downsample_methods + ['count']
             for method in methods:
                 result = getattr(f.resample(freq), method)()
-
-                expected = pd.Series([])
+                expected = f.copy()
                 expected.index = f.index._shallow_copy(freq=freq)
                 assert_index_equal(result.index, expected.index)
                 self.assertEqual(result.index.freq, expected.index.freq)
-                assert_series_equal(result, expected, check_dtype=False)
+                assert_frame_equal(result, expected, check_dtype=False)
 
             # test size for GH13212 (currently stays as df)
 
+    def test_resample_size_empty_dataframe(self):
+        # GH14962
+        index = self.create_series().index[:0]
+        f = DataFrame(index=index)
+
+        for freq in ['M', 'D', 'H']:
+            result = f.resample(freq).size()
+
+            if isinstance(result.index, PeriodIndex) and freq == 'H':
+                expected = f.copy()
+                assert_equal = assert_frame_equal
+            else:
+                expected = Series([])
+                assert_equal = assert_series_equal
+                
+            expected.index = f.index._shallow_copy(freq=freq)
+            assert_index_equal(result.index, expected.index)
+            self.assertEqual(result.index.freq, expected.index.freq)
+            assert_equal(result, expected, check_dtype=False)
+
     def test_resample_empty_dtypes(self):
 
         # Empty series were sometimes causing a segfault (for the functions
@@ -824,16 +843,6 @@ def test_resample_loffset_arg_type(self):
                 assert_frame_equal(result_agg, expected)
                 assert_frame_equal(result_how, expected)
 
-    def test_resample_empty_dataframe_with_size(self):
-        # GH 14962
-        index = pd.DatetimeIndex([], freq='M')
-        df = pd.DataFrame([], index=index)
-
-        for freq in ['M', 'D', 'H']:
-            result = df.resample(freq).size()
-            expected = pd.Series([], index=index, dtype='int64')
-            assert_series_equal(result, expected)
-
 
 class TestDatetimeIndex(Base, tm.TestCase):
     _multiprocess_can_split_ = True