REF: Series inplace methods return None. #1893

Author: wesm

pandas/core/series.py

@@ -594,7 +594,7 @@ def where(self, cond, other=nan, inplace=False):
         ser = self if inplace else self.copy()
         if not isinstance(other, (list, tuple, np.ndarray)):
             ser._set_with(~cond, other)
-            return ser
+            return None if inplace else ser
 
         if isinstance(other, Series):
             other = other.reindex(ser.index)
@@ -603,7 +603,7 @@ def where(self, cond, other=nan, inplace=False):
 
         np.putmask(ser, ~cond, other)
 
-        return ser
+        return None if inplace else ser
 
     def mask(self, cond):
         """
@@ -903,7 +903,7 @@ def reset_index(self, level=None, drop=False, name=None, inplace=False):
                 self.index = new_index
                 # set name if it was passed, otherwise, keep the previous name
                 self.name = name or self.name
-                return self
+                return
             else:
                 return Series(self.values.copy(), index=new_index,
                               name=self.name)
@@ -2246,7 +2246,7 @@ def apply(self, func, convert_dtype=True, args=(), **kwds):
             return Series(mapped, index=self.index, name=self.name)
 
     def align(self, other, join='outer', level=None, copy=True,
-              fill_value=None, method=None, inplace=False, limit=None):
+              fill_value=None, method=None, limit=None):
         """
         Align two Series object with the specified join method
 
@@ -2419,7 +2419,7 @@ def fillna(self, value=None, method=None, inplace=False,
         filled : Series
         """
         if not self._can_hold_na:
-            return self.copy() if not inplace else self
+            return self.copy() if not inplace else None
 
         if value is not None:
             if method is not None:
@@ -2445,7 +2445,7 @@ def fillna(self, value=None, method=None, inplace=False,
             else:
                 result = Series(values, index=self.index, name=self.name)
 
-        return result
+        return result if not inplace else None
 
     def ffill(self, inplace=False, limit=None):
         return self.fillna(method='ffill', inplace=inplace, limit=limit)
@@ -2492,7 +2492,6 @@ def replace(self, to_replace, value=None, method='pad', inplace=False,
         def _rep_one(s, to_rep, v):  # replace single value
             mask = com.mask_missing(s.values, to_rep)
             np.putmask(s.values, mask, v)
-            return s
 
         def _rep_dict(rs, to_rep):  # replace {[src] -> dest}
 
@@ -2513,26 +2512,24 @@ def _rep_dict(rs, to_rep):  # replace {[src] -> dest}
             else:  # if no risk of clobbering then simple
                 for d, sset in dd.iteritems():
                     _rep_one(rs, sset, d)
-            return rs
 
         if np.isscalar(to_replace):
             to_replace = [to_replace]
 
         if isinstance(to_replace, dict):
-            return _rep_dict(result, to_replace)
-
-        if isinstance(to_replace, (list, np.ndarray)):
+            _rep_dict(result, to_replace)
+        elif isinstance(to_replace, (list, np.ndarray)):
 
             if isinstance(value, (list, np.ndarray)):  # check same length
                 vl, rl = len(value), len(to_replace)
                 if vl == rl:
-                    return _rep_dict(result, dict(zip(to_replace, value)))
-                raise ValueError('Got %d to replace but %d values' % (rl, vl))
+                    _rep_dict(result, dict(zip(to_replace, value)))
+                else:
+                    raise ValueError('Got %d to replace but %d values'
+                                     % (rl, vl))
 
             elif value is not None:  # otherwise all replaced with same value
-
-                return _rep_one(result, to_replace, value)
-
+                _rep_one(result, to_replace, value)
             else:  # method
                 if method is None:  # pragma: no cover
                     raise ValueError('must specify a fill method')
@@ -2544,10 +2541,11 @@ def _rep_dict(rs, to_rep):  # replace {[src] -> dest}
                 if not inplace:
                     result = Series(result.values, index=self.index,
                                     name=self.name)
-                return result
+        else:
+            raise ValueError('Unrecognized to_replace type %s' %
+                             type(to_replace))
 
-        raise ValueError('Unrecognized to_replace type %s' %
-                         type(to_replace))
+        return result if not inplace else None
 
     def isin(self, values):
         """
@@ -2895,7 +2893,7 @@ def rename(self, mapper, inplace=False):
         result = self if inplace else self.copy()
         result.index = [mapper_f(x) for x in self.index]
 
-        return result
+        return result if not inplace else None
 
     @property
     def weekday(self):

pandas/src/parser/tokenizer.c

@@ -1,6 +1,9 @@
 /*
 
-Copyright (c) 2012, Lambda Foundry, Inc.
+Copyright (c) 2012, Lambda Foundry, Inc., except where noted
+
+Incorporates components of WarrenWeckesser/textreader, licensed under 3-clause
+BSD
 
 See LICENSE for the license
 

pandas/src/parser/tokenizer.h

@@ -1,6 +1,9 @@
 /*
 
-Copyright (c) 2012, Lambda Foundry, Inc.
+Copyright (c) 2012, Lambda Foundry, Inc., except where noted
+
+Incorporates components of WarrenWeckesser/textreader, licensed under 3-clause
+BSD
 
 See LICENSE for the license
 

pandas/tests/test_series.py

@@ -974,7 +974,10 @@ def test_where_inplace(self):
         cond = s > 0
 
         rs = s.copy()
-        rs.where(cond, inplace=True)
+
+        res = rs.where(cond, inplace=True)
+        self.assertTrue(res is None)
+
         assert_series_equal(rs.dropna(), s[cond])
         assert_series_equal(rs, s.where(cond))
 
@@ -2883,7 +2886,9 @@ def test_rename(self):
     def test_rename_inplace(self):
         renamer = lambda x: x.strftime('%Y%m%d')
         expected = renamer(self.ts.index[0])
-        self.ts.rename(renamer, inplace=True)
+        res = self.ts.rename(renamer, inplace=True)
+
+        self.assertTrue(res is None)
         self.assertEqual(self.ts.index[0], expected)
 
     def test_preserveRefs(self):
@@ -2900,7 +2905,10 @@ def test_ne(self):
     def test_pad_nan(self):
         x = TimeSeries([np.nan, 1., np.nan, 3., np.nan],
                        ['z', 'a', 'b', 'c', 'd'], dtype=float)
-        x.fillna(method='pad', inplace=True)
+
+        res = x.fillna(method='pad', inplace=True)
+        self.assertTrue(res is None)
+
         expected = TimeSeries([np.nan, 1.0, 1.0, 3.0, 3.0],
                                 ['z', 'a', 'b', 'c', 'd'], dtype=float)
         assert_series_equal(x[1:], expected[1:])
@@ -2950,7 +2958,7 @@ def test_isin(self):
 
     def test_fillna_int(self):
         s = Series(np.random.randint(-100, 100, 50))
-        self.assert_(s.fillna(method='ffill', inplace=True) is s)
+        self.assert_(s.fillna(method='ffill', inplace=True) is None)
         assert_series_equal(s.fillna(method='ffill', inplace=False), s)
 
 #-------------------------------------------------------------------------------
@@ -2986,11 +2994,11 @@ def test_fillna_inplace(self):
         x = Series([nan, 1., nan, 3., nan],['z','a','b','c','d'])
         y = x.copy()
 
-        y2 = y.fillna(value=0, inplace=True)
-        self.assert_(y is y2)
+        res = y.fillna(value=0, inplace=True)
+        self.assert_(res is None)
 
         expected = x.fillna(value=0)
-        assert_series_equal(y2, expected)
+        assert_series_equal(y, expected)
 
     def test_fillna_invalid_method(self):
         try:
@@ -3016,8 +3024,10 @@ def test_replace(self):
 
         # replace list with a single value
         rs = ser.replace([np.nan], -1, inplace=True)
+        self.assertTrue(rs is None)
+
         exp = ser.fillna(-1)
-        assert_series_equal(rs, exp)
+        assert_series_equal(ser, exp)
 
         rs = ser.replace(0., np.nan)
         ser[ser == 0.] = np.nan
@@ -3060,7 +3070,10 @@ def test_replace(self):
         assert_almost_equal(rs4[4], ser[5])
 
         # replace inplace
-        ser.replace([np.nan, 'foo', 'bar'], -1, inplace=True)
+        res = ser.replace([np.nan, 'foo', 'bar'], -1, inplace=True)
+
+        self.assertTrue(res is None)
+
         self.assert_((ser[:5] == -1).all())
         self.assert_((ser[6:10] == -1).all())
         self.assert_((ser[20:30] == -1).all())
@@ -3314,7 +3327,8 @@ def test_reset_index(self):
         #check inplace
         s = ser.reset_index(drop=True)
         s2 = ser
-        s2.reset_index(drop=True, inplace=True)
+        res = s2.reset_index(drop=True, inplace=True)
+        self.assertTrue(res is None)
         assert_series_equal(s, s2)
 
         #level