BUG: DataFrame arithmetic with subclass where constructor is not the subclass itself (#43897)

Author: jbrockmendel

doc/source/whatsnew/v1.4.0.rst

@@ -408,6 +408,8 @@ Numeric
 - Bug in :meth:`DataFrame.rank` raising ``ValueError`` with ``object`` columns and ``method="first"`` (:issue:`41931`)
 - Bug in :meth:`DataFrame.rank` treating missing values and extreme values as equal (for example ``np.nan`` and ``np.inf``), causing incorrect results when ``na_option="bottom"`` or ``na_option="top`` used (:issue:`41931`)
 - Bug in ``numexpr`` engine still being used when the option ``compute.use_numexpr`` is set to ``False`` (:issue:`32556`)
+- Bug in :class:`DataFrame` arithmetic ops with a subclass whose :meth:`_constructor` attribute is a callable other than the subclass itself (:issue:`43201`)
+-
 
 Conversion
 ^^^^^^^^^^

pandas/core/frame.py

@@ -6954,7 +6954,7 @@ def _dispatch_frame_op(self, right, func: Callable, axis: int | None = None):
             # i.e. scalar, faster than checking np.ndim(right) == 0
             with np.errstate(all="ignore"):
                 bm = self._mgr.apply(array_op, right=right)
-            return type(self)(bm)
+            return self._constructor(bm)
 
         elif isinstance(right, DataFrame):
             assert self.index.equals(right.index)
@@ -6975,7 +6975,7 @@ def _dispatch_frame_op(self, right, func: Callable, axis: int | None = None):
                     right._mgr,  # type: ignore[arg-type]
                     array_op,
                 )
-            return type(self)(bm)
+            return self._constructor(bm)
 
         elif isinstance(right, Series) and axis == 1:
             # axis=1 means we want to operate row-by-row

pandas/tests/frame/test_arithmetic.py

@@ -1,5 +1,6 @@
 from collections import deque
 from datetime import datetime
+import functools
 import operator
 import re
 
@@ -1845,3 +1846,39 @@ def test_bool_frame_mult_float():
     result = df * 1.0
     expected = DataFrame(np.ones((2, 2)), list("ab"), list("cd"))
     tm.assert_frame_equal(result, expected)
+
+
+def test_frame_op_subclass_nonclass_constructor():
+    # GH#43201 subclass._constructor is a function, not the subclass itself
+
+    class SubclassedSeries(Series):
+        @property
+        def _constructor(self):
+            return SubclassedSeries
+
+        @property
+        def _constructor_expanddim(self):
+            return SubclassedDataFrame
+
+    class SubclassedDataFrame(DataFrame):
+        _metadata = ["my_extra_data"]
+
+        def __init__(self, my_extra_data, *args, **kwargs):
+            self.my_extra_data = my_extra_data
+            super().__init__(*args, **kwargs)
+
+        @property
+        def _constructor(self):
+            return functools.partial(type(self), self.my_extra_data)
+
+        @property
+        def _constructor_sliced(self):
+            return SubclassedSeries
+
+    sdf = SubclassedDataFrame("some_data", {"A": [1, 2, 3], "B": [4, 5, 6]})
+    result = sdf * 2
+    expected = SubclassedDataFrame("some_data", {"A": [2, 4, 6], "B": [8, 10, 12]})
+    tm.assert_frame_equal(result, expected)
+
+    result = sdf + sdf
+    tm.assert_frame_equal(result, expected)