fixup! API: Accept 'axis' keyword argument for reindex

Author: TomAugspurger

doc/source/whatsnew/v0.21.0.txt

@@ -109,8 +109,10 @@ For example:
     # the following is now equivalent
     df.drop(columns=['B', 'C'])
 
-``rename``, ``reindex`` now also accepts axis keyword
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+.. _whatsnew_0210.enhancements.rename_reindex_axis:
+
+``rename``, ``reindex`` now also accept axis keyword
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 The :meth:`DataFrame.rename` and :meth:`DataFrame.reindex` methods have gained
 the ``axis`` keyword to specify the axis to target with the operation. This
@@ -121,18 +123,23 @@ Here's ``rename``:
 
 .. ipython:: 
 
-    df = pd.DataFrame({"A": [1, 2, 3], "B": [4, 5, 6]})
-    df.rename(str.lower, axis='columns')
-    df.rename(id, axis='index')
+   df = pd.DataFrame({"A": [1, 2, 3], "B": [4, 5, 6]})
+   df.rename(str.lower, axis='columns')
+   df.rename(id, axis='index')
 
 And ``reindex``:
 
 .. ipython::
 
-    df.reindex(['A', 'B', 'C'], axis='columns')
-    df.reindex([0, 1, 3], axis='index')
+   df.reindex(['A', 'B', 'C'], axis='columns')
+   df.reindex([0, 1, 3], axis='index')
 
 The ``.rename(index=id, columns=str.lower)`` style continues to work as before.
+
+.. ipython::
+
+   df.rename(index=id, columns=str.lower)
+
 We *highly* encourage using named arguments to avoid confusion when using either
 style.
 

pandas/core/frame.py

@@ -115,10 +115,10 @@
     versionadded_to_excel='',
     optional_mapper="""mapper : dict-like or function
             Applied to the axis specified by `axis`""",
-    optional_labels="""labels : array-like
+    optional_labels="""labels : array-like, optional
             New labels / index to conform the axis specified by 'axis' to.""",
     optional_axis="""axis : int or str, optional
-            Axis to target. Can be either the axis name ('rows', 'columns')
+            Axis to target. Can be either the axis name ('index', 'columns')
             or number (0, 1).""",
 )
 
@@ -2776,7 +2776,7 @@ def reindexer(value):
 
     def _validate_axis_style_args(self, arg, arg_name, index, columns,
                                   axis, method_name):
-        if axis is not None:
+        if axis != 0:
             # Using "axis" style, along with a positional arg
             # Both index and columns should be None then
             axis = self._get_axis_name(axis)
@@ -2940,7 +2940,7 @@ def align(self, other, join='outer', axis=None, level=None, copy=True,
                                             broadcast_axis=broadcast_axis)
 
     @Appender(_shared_docs['reindex'] % _shared_doc_kwargs)
-    def reindex(self, labels=None, index=None, columns=None, axis=None,
+    def reindex(self, labels=None, index=None, columns=None, axis=0,
                 **kwargs):
         index, columns = self._validate_axis_style_args(labels, 'labels',
                                                         index, columns,
@@ -2957,7 +2957,7 @@ def reindex_axis(self, labels, axis=0, method=None, level=None, copy=True,
                                         limit=limit, fill_value=fill_value)
 
     @Appender(_shared_docs['rename'] % _shared_doc_kwargs)
-    def rename(self, mapper=None, index=None, columns=None, axis=None,
+    def rename(self, mapper=None, index=None, columns=None, axis=0,
                **kwargs):
         index, columns = self._validate_axis_style_args(mapper, 'mapper',
                                                         index, columns,

pandas/core/generic.py

@@ -2796,8 +2796,8 @@ def sort_index(self, axis=0, level=None, ascending=True, inplace=False,
 
         Note that ``.reindex`` can be called by specifying either
 
-            * One or both of ``index`` and ``columns``
-            * ``labels`` and ``axis``
+        * One or both of ``index`` and ``columns``
+        * ``labels`` and ``axis``
 
         Create a dataframe with some fictional data.
 

pandas/tests/frame/test_alter_axes.py

@@ -837,7 +837,8 @@ def test_rename_objects(self):
         assert 'FOO' in renamed
         assert 'foo' not in renamed
 
-    def test_rename_columns(self):
+    def test_rename_axis_style(self):
+        # https://github.com/pandas-dev/pandas/issues/12392
         df = pd.DataFrame({"A": [1, 2], "B": [1, 2]}, index=['X', 'Y'])
         expected = pd.DataFrame({"a": [1, 2], "b": [1, 2]}, index=['X', 'Y'])
 
@@ -875,12 +876,14 @@ def test_rename_mapper_multi(self):
         assert_frame_equal(result, expected)
 
     def test_rename_positional_named(self):
+        # https://github.com/pandas-dev/pandas/issues/12392
         df = pd.DataFrame({"a": [1, 2], "b": [1, 2]}, index=['X', 'Y'])
         result = df.rename(str.lower, columns=str.upper)
         expected = pd.DataFrame({"A": [1, 2], "B": [1, 2]}, index=['x', 'y'])
         assert_frame_equal(result, expected)
 
-    def test_rename_raises(self):
+    def test_rename_axis_style_raises(self):
+        # https://github.com/pandas-dev/pandas/issues/12392
         df = pd.DataFrame({"A": [1, 2], "B": [1, 2]}, index=['0', '1'])
 
         # Named target and axis
@@ -908,6 +911,7 @@ def test_rename_raises(self):
             df.rename(str.lower, str.lower, str.lower)
 
     def test_drop_api_equivalence(self):
+        # https://github.com/pandas-dev/pandas/issues/12392
         # equivalence of the labels/axis and index/columns API's
         df = DataFrame([[1, 2, 3], [3, 4, 5], [5, 6, 7]],
                        index=['a', 'b', 'c'],

pandas/tests/frame/test_axis_select_reindex.py

@@ -448,6 +448,7 @@ def test_reindex_dups(self):
         pytest.raises(ValueError, df.reindex, index=list(range(len(df))))
 
     def test_reindex_axis_style(self):
+        # https://github.com/pandas-dev/pandas/issues/12392
         df = pd.DataFrame({"A": [1, 2, 3], "B": [4, 5, 6]})
         expected = pd.DataFrame({"A": [1, 2, np.nan], "B": [4, 5, np.nan]},
                                 index=[0, 1, 3])
@@ -461,6 +462,7 @@ def test_reindex_axis_style(self):
         assert_frame_equal(result, expected)
 
     def test_reindex_positional_warns(self):
+        # https://github.com/pandas-dev/pandas/issues/12392
         df = pd.DataFrame({"A": [1, 2, 3], "B": [4, 5, 6]})
         expected = pd.DataFrame({"A": [1., 2], 'B': [4., 5],
                                  "C": [np.nan, np.nan]})
@@ -470,6 +472,7 @@ def test_reindex_positional_warns(self):
         assert_frame_equal(result, expected)
 
     def test_reindex_axis_style_raises(self):
+        # https://github.com/pandas-dev/pandas/issues/12392
         df = pd.DataFrame({"A": [1, 2, 3], 'B': [4, 5, 6]})
         with tm.assert_raises_regex(TypeError, ''):
             df.reindex([0, 1], ['A'], axis=1)
@@ -493,12 +496,14 @@ def test_reindex_axis_style_raises(self):
             df.reindex([0, 1], [0], ['A'])
 
     def test_reindex_single_named_indexer(self):
+        # https://github.com/pandas-dev/pandas/issues/12392
         df = pd.DataFrame({"A": [1, 2, 3], "B": [1, 2, 3]})
         result = df.reindex([0, 1], columns=['A'])
         expected = pd.DataFrame({"A": [1, 2]})
         assert_frame_equal(result, expected)
 
     def test_reindex_api_equivalence(self):
+        # https://github.com/pandas-dev/pandas/issues/12392
         # equivalence of the labels/axis and index/columns API's
         df = DataFrame([[1, 2, 3], [3, 4, 5], [5, 6, 7]],
                        index=['a', 'b', 'c'],