BUG: Fixe unintentionally added suffix in DataFrame.apply/agg and Series.apply/agg (pandas-dev#36231)

Author: charlesdong1991

doc/source/whatsnew/v1.1.3.rst

@@ -14,6 +14,7 @@ including other versions of pandas.
 
 Fixed regressions
 ~~~~~~~~~~~~~~~~~
+- Fixed regression in :meth:`DataFrame.agg`, :meth:`DataFrame.apply`, :meth:`Series.agg`, and :meth:`Series.apply` where internal suffix is exposed to the users when no relabelling is applied (:issue:`36189`)
 - Fixed regression in :class:`IntegerArray` unary plus and minus operations raising a ``TypeError`` (:issue:`36063`)
 - Fixed regression in :meth:`Series.__getitem__` incorrectly raising when the input was a tuple (:issue:`35534`)
 - Fixed regression in :meth:`Series.__getitem__` incorrectly raising when the input was a frozenset (:issue:`35747`)

pandas/core/aggregation.py

@@ -63,7 +63,7 @@ def reconstruct_func(
  Examples
  --------
  >>> reconstruct_func(None, **{"foo": ("col", "min")})
- (True, defaultdict(None, {'col': ['min']}), ('foo',), array([0]))
+ (True, defaultdict(<class 'list'>, {'col': ['min']}), ('foo',), array([0]))
 
  >>> reconstruct_func("min")
  (False, 'min', None, None)
@@ -87,7 +87,6 @@ def reconstruct_func(
 
  if relabeling:
  func, columns, order = normalize_keyword_aggregation(kwargs)
- func = maybe_mangle_lambdas(func)
 
  return relabeling, func, columns, order
 

pandas/core/groupby/generic.py

@@ -951,6 +951,7 @@ def aggregate(self, func=None, *args, engine=None, engine_kwargs=None, **kwargs)
  return self.obj._constructor(result, index=index, columns=data.columns)
 
  relabeling, func, columns, order = reconstruct_func(func, **kwargs)
+ func = maybe_mangle_lambdas(func)
 
  result, how = self._aggregate(func, *args, **kwargs)
  if how is None:

pandas/tests/frame/apply/test_frame_apply.py

@@ -1534,3 +1534,14 @@ def test_apply_empty_list_reduce():
  result = df.apply(lambda x: [], result_type="reduce")
  expected = pd.Series({"a": [], "b": []}, dtype=object)
  tm.assert_series_equal(result, expected)
+
+
+def test_apply_no_suffix_index():
+ # GH36189
+ pdf = pd.DataFrame([[4, 9]] * 3, columns=["A", "B"])
+ result = pdf.apply(["sum", lambda x: x.sum(), lambda x: x.sum()])
+ expected = pd.DataFrame(
+ {"A": [12, 12, 12], "B": [27, 27, 27]}, index=["sum", "<lambda>", "<lambda>"]
+ )
+
+ tm.assert_frame_equal(result, expected)

pandas/tests/groupby/aggregate/test_aggregate.py

@@ -1153,3 +1153,18 @@ def test_nonagg_agg():
  expected = g.agg("cumsum")
 
  tm.assert_frame_equal(result, expected)
+
+
+def test_agg_no_suffix_index():
+ # GH36189
+ df = pd.DataFrame([[4, 9]] * 3, columns=["A", "B"])
+ result = df.agg(["sum", lambda x: x.sum(), lambda x: x.sum()])
+ expected = pd.DataFrame(
+ {"A": [12, 12, 12], "B": [27, 27, 27]}, index=["sum", "<lambda>", "<lambda>"]
+ )
+ tm.assert_frame_equal(result, expected)
+
+ # test Series case
+ result = df["A"].agg(["sum", lambda x: x.sum(), lambda x: x.sum()])
+ expected = pd.Series([12, 12, 12], index=["sum", "<lambda>", "<lambda>"], name="A")
+ tm.assert_series_equal(result, expected)

pandas/tests/series/apply/test_series_apply.py

@@ -445,6 +445,14 @@ def test_agg_cython_table_raises(self, series, func, expected):
  # e.g. Series('a b'.split()).cumprod() will raise
  series.agg(func)
 
+ def test_series_apply_no_suffix_index(self):
+ # GH36189
+ s = pd.Series([4] * 3)
+ result = s.apply(["sum", lambda x: x.sum(), lambda x: x.sum()])
+ expected = pd.Series([12, 12, 12], index=["sum", "<lambda>", "<lambda>"])
+
+ tm.assert_series_equal(result, expected)
+
 
 class TestSeriesMap:
  def test_map(self, datetime_series):