ENH: Implement feedback (#13473)

Author: MaxVanDeursen

doc/source/whatsnew/v0.25.0.rst

@@ -25,7 +25,7 @@ Other Enhancements
 - ``Series.str`` has gained :meth:`Series.str.casefold` method to removes all case distinctions present in a string (:issue:`25405`)
 - :meth:`DataFrame.set_index` now works for instances of ``abc.Iterator``, provided their output is of the same length as the calling frame (:issue:`22484`, :issue:`24984`)
 - :meth:`DatetimeIndex.union` now supports the ``sort`` argument. The behaviour of the sort parameter matches that of :meth:`Index.union` (:issue:`24994`)
--
+- :meth:`DataFrame.rename` now supports the ``errors`` argument to raise errors when attempting to rename nonexistent keys (:issue:`13473`)
 
 .. _whatsnew_0250.api_breaking:
 

pandas/core/frame.py

@@ -3958,11 +3958,12 @@ def rename(self, *args, **kwargs):
         Raises
         ------
         KeyError
-            If any of the labels is not found in the selected axis.
+            If any of the labels is not found in the selected axis and
+            "errors='raise'".
 
         See Also
         --------
-        DataFrame.rename_axis: Set the name of the axis for the index or
+        DataFrame.rename_axis : Set the name of the axis for the index or
          columns.
 
         Examples
@@ -3989,6 +3990,10 @@ def rename(self, *args, **kwargs):
         1  2  5
         2  3  6
 
+        >>> df.rename(index=str, columns={"A": "a", "C": "c"}, errors="raise")
+        Traceback (most recent call last):
+        KeyError: ['C'] not found in axis
+
         Using axis-style parameters
 
         >>> df.rename(str.lower, axis='columns')

pandas/tests/frame/test_alter_axes.py

@@ -871,27 +871,21 @@ def test_rename_bug2(self):
                              columns=["a"])
         tm.assert_frame_equal(df, expected)
 
-    def test_rename_errors(self):
-        # GH 13473
-        # rename now works with errors parameter
-
-        # Error has to be thrown and is thrown
+    def test_rename_errors_raises(self):
         df = DataFrame(columns=['A', 'B', 'C', 'D'])
-        with pytest.raises(KeyError):
+        with pytest.raises(KeyError, match='\'E\'] not found in axis'):
             df.rename(columns={'A': 'a', 'E': 'e'}, errors='raise')
 
-        # Error should be ignored
-        renamed = df.rename(columns={'A': 'a', 'E': 'e'})
-        expected = DataFrame(columns=['a', 'B', 'C', 'D'])
-        tm.assert_frame_equal(renamed, expected)
-
-        # Correct behaviour with raising errors.
-        renamed = df.rename(columns={'A': 'a'}, errors='raise')
-        expected = DataFrame(columns=['a', 'B', 'C', 'D'])
-        tm.assert_frame_equal(renamed, expected)
-
-        renamed = df.rename(columns=str.lower, errors='raise')
-        expected = DataFrame(columns=['a', 'b', 'c', 'd'])
+    @pytest.mark.parametrize('mapper, errors, expected_columns', [
+        ({'A': 'a', 'E': 'e'}, 'ignore', ['a', 'B', 'C', 'D']),
+        ({'A': 'a'}, 'raise', ['a', 'B', 'C', 'D']),
+        (str.lower, 'raise', ['a', 'b', 'c', 'd'])])
+    def test_rename_errors(self, mapper, errors, expected_columns):
+        # GH 13473
+        # rename now works with errors parameter
+        df = DataFrame(columns=['A', 'B', 'C', 'D'])
+        renamed = df.rename(columns=mapper, errors=errors)
+        expected = DataFrame(columns=expected_columns)
         tm.assert_frame_equal(renamed, expected)
 
     def test_reorder_levels(self):