Fixed metadata propagation in Dataframe.idxmax and Dataframe.idxmin #… (#47821)

* Fixed metadata propagation in Dataframe.idxmax and Dataframe.idxmin #28283 * fixing PEP 8 issues * removing unnecessary pytest.param() * removing unnecessary pytest.param

Author: SomtochiUmeh

pandas/core/frame.py

@@ -11010,7 +11010,8 @@ def idxmin(
 
  index = data._get_axis(axis)
  result = [index[i] if i >= 0 else np.nan for i in indices]
- return data._constructor_sliced(result, index=data._get_agg_axis(axis))
+ final_result = data._constructor_sliced(result, index=data._get_agg_axis(axis))
+ return final_result.__finalize__(self, method="idxmin")
 
  @doc(_shared_docs["idxmax"], numeric_only_default="False")
  def idxmax(
@@ -11035,7 +11036,8 @@ def idxmax(
 
  index = data._get_axis(axis)
  result = [index[i] if i >= 0 else np.nan for i in indices]
- return data._constructor_sliced(result, index=data._get_agg_axis(axis))
+ final_result = data._constructor_sliced(result, index=data._get_agg_axis(axis))
+ return final_result.__finalize__(self, method="idxmax")
 
  def _get_agg_axis(self, axis_num: int) -> Index:
  """

pandas/tests/generic/test_finalize.py

@@ -226,17 +226,9 @@
  pytest.param(
  (pd.DataFrame, frame_data, operator.methodcaller("nunique")),
  ),
- pytest.param(
- (pd.DataFrame, frame_data, operator.methodcaller("idxmin")),
- marks=not_implemented_mark,
- ),
- pytest.param(
- (pd.DataFrame, frame_data, operator.methodcaller("idxmax")),
- marks=not_implemented_mark,
- ),
- pytest.param(
- (pd.DataFrame, frame_data, operator.methodcaller("mode")),
- ),
+ (pd.DataFrame, frame_data, operator.methodcaller("idxmin")),
+ (pd.DataFrame, frame_data, operator.methodcaller("idxmax")),
+ (pd.DataFrame, frame_data, operator.methodcaller("mode")),
  pytest.param(
  (pd.Series, [0], operator.methodcaller("mode")),
  marks=not_implemented_mark,