BUG: Don't copy DataFrame columns as metadata (pandas-dev#37205)

Author: TomAugspurger

doc/source/whatsnew/v1.2.0.rst

@@ -523,6 +523,7 @@ Other
 
 - Bug in :meth:`DataFrame.replace` and :meth:`Series.replace` incorrectly raising ``AssertionError`` instead of ``ValueError`` when invalid parameter combinations are passed (:issue:`36045`)
 - Bug in :meth:`DataFrame.replace` and :meth:`Series.replace` with numeric values and string ``to_replace`` (:issue:`34789`)
+- Fixed bug in metadata propagation incorrectly copying DataFrame columns as metadata when the column name overlaps with the metadata name (:issue:`37037`)
 - Fixed metadata propagation in the :class:`Series.dt` and :class:`Series.str` accessors (:issue:`28283`)
 - Bug in :meth:`Index.union` behaving differently depending on whether operand is a :class:`Index` or other list-like (:issue:`36384`)
 - Passing an array with 2 or more dimensions to the :class:`Series` constructor now raises the more specific ``ValueError``, from a bare ``Exception`` previously (:issue:`35744`)

pandas/core/generic.py

@@ -5364,7 +5364,7 @@ def __finalize__(
 
             self.flags.allows_duplicate_labels = other.flags.allows_duplicate_labels
             # For subclasses using _metadata.
-            for name in self._metadata:
+            for name in set(self._metadata) & set(other._metadata):
                 assert isinstance(name, str)
                 object.__setattr__(self, name, getattr(other, name, None))
 

pandas/tests/generic/test_finalize.py

@@ -786,3 +786,11 @@ def test_groupby_finalize_not_implemented(obj, method):
     obj.attrs = {"a": 1}
     result = method(obj.groupby([0, 0]))
     assert result.attrs == {"a": 1}
+
+
+def test_finalize_frame_series_name():
+    # https://github.com/pandas-dev/pandas/pull/37186/files#r506978889
+    # ensure we don't copy the column `name` to the Series.
+    df = pd.DataFrame({"name": [1, 2]})
+    result = pd.Series([1, 2]).__finalize__(df)
+    assert result.name is None