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

Author: TomAugspurger

pandas/core/frame.py

@@ -65,6 +65,7 @@
                                 _values_from_object,
                                 _maybe_box_datetimelike,
                                 _dict_compat,
+                                _all_not_none,
                                 standardize_mapping)
 from pandas.core.generic import NDFrame, _shared_docs
 from pandas.core.index import (Index, MultiIndex, _ensure_index,
@@ -2792,15 +2793,15 @@ def _validate_axis_style_args(self, arg, arg_name, index, columns,
             elif axis == 'columns':
                 columns = arg
 
-        elif all(x is not None for x in (arg, index, columns)):
+        elif _all_not_none(arg, index, columns):
             msg = (
                 "Cannot specify all of '{arg_name}', 'index', and 'columns'. "
                 "Specify either {arg_name} and 'axis', or 'index' and "
                 "'columns'."
             ).format(arg_name=arg_name)
             raise TypeError(msg)
 
-        elif axis is None and (arg is not None and index is not None):
+        elif _all_not_none(arg, index):
             # This is the "ambiguous" case, so emit a warning
             msg = (
                 "Interpreting call to '.{method_name}(a, b)' as "
@@ -2809,7 +2810,7 @@ def _validate_axis_style_args(self, arg, arg_name, index, columns,
             ).format(method_name=method_name)
             warnings.warn(msg, stacklevel=3)
             index, columns = arg, index
-        elif index is None and columns is None:
+        elif index is None:
             index = arg
         return index, columns
 

pandas/tests/frame/test_alter_axes.py

@@ -874,6 +874,12 @@ def test_rename_mapper_multi(self):
         expected = df.rename(index=str.upper)
         assert_frame_equal(result, expected)
 
+    def test_rename_positional_named(self):
+        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):
         df = pd.DataFrame({"A": [1, 2], "B": [1, 2]}, index=['0', '1'])
 

pandas/tests/frame/test_axis_select_reindex.py

@@ -492,6 +492,12 @@ def test_reindex_axis_style_raises(self):
         with tm.assert_raises_regex(TypeError, ''):
             df.reindex([0, 1], [0], ['A'])
 
+    def test_reindex_single_named_indexer(self):
+        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):
         # equivalence of the labels/axis and index/columns API's
         df = DataFrame([[1, 2, 3], [3, 4, 5], [5, 6, 7]],