REF: consistent ndarray-wrapping for lists in arithmetic ops

Author: jbrockmendel

pandas/core/arrays/masked.py

@@ -924,6 +924,9 @@ def _maybe_mask_result(
 
             return IntegerArray(result, mask, copy=False)
 
+        elif result.dtype == object:
+            result[mask] = self.dtype.na_value
+            return result
         else:
             result[mask] = np.nan
             return result

pandas/core/ops/array_ops.py

@@ -261,6 +261,10 @@ def arithmetic_op(left: ArrayLike, right: Any, op):
     #  and `maybe_prepare_scalar_for_op` has already been called on `right`
     # We need to special-case datetime64/timedelta64 dtypes (e.g. because numpy
     # casts integer dtypes to timedelta64 when operating with timedelta64 - GH#22390)
+    if isinstance(right, list):
+        # GH#62423
+        right = np.array(right)
+    right = ensure_wrapped_if_datetimelike(right)
 
     if (
         should_extension_dispatch(left, right)
@@ -311,6 +315,7 @@ def comparison_op(left: ArrayLike, right: Any, op) -> ArrayLike:
         # We don't catch tuple here bc we may be comparing e.g. MultiIndex
         #  to a tuple that represents a single entry, see test_compare_tuple_strs
         rvalues = np.asarray(rvalues)
+        rvalues = ensure_wrapped_if_datetimelike(rvalues)
 
     if isinstance(rvalues, (np.ndarray, ABCExtensionArray)):
         # TODO: make this treatment consistent across ops and classes.

pandas/core/ops/common.py

@@ -7,10 +7,13 @@
 from functools import wraps
 from typing import TYPE_CHECKING
 
+import numpy as np
+
 from pandas._libs.lib import item_from_zerodim
 from pandas._libs.missing import is_matching_na
 
 from pandas.core.dtypes.generic import (
+    ABCExtensionArray,
     ABCIndex,
     ABCSeries,
 )
@@ -67,6 +70,15 @@ def new_method(self, other):
 
         other = item_from_zerodim(other)
 
+        if isinstance(self, ABCExtensionArray):
+            if isinstance(other, list):
+                # See GH#62423
+                other = np.array(other)
+                if other.dtype.kind in "mM":
+                    from pandas.core.construction import ensure_wrapped_if_datetimelike
+
+                    other = ensure_wrapped_if_datetimelike(other)
+
         return method(self, other)
 
     # error: Incompatible return value type (got "Callable[[Any, Any], Any]",

pandas/tests/indexes/categorical/test_category.py

@@ -329,6 +329,7 @@ def test_disallow_addsub_ops(self, func, op_name):
                 f"cannot perform {op_name} with this index type: CategoricalIndex",
                 "can only concatenate list",
                 rf"unsupported operand type\(s\) for [\+-]: {cat_or_list}",
+                "Object with dtype category cannot perform the numpy op ",
             ]
         )
         with pytest.raises(TypeError, match=msg):

pandas/tests/series/test_arithmetic.py

@@ -335,12 +335,12 @@ def test_mask_div_propagate_na_for_non_na_dtype(self):
         result = ser2 / ser1
         tm.assert_series_equal(result, expected)
 
-    @pytest.mark.parametrize("val, dtype", [(3, "Int64"), (3.5, "Float64")])
-    def test_add_list_to_masked_array(self, val, dtype):
+    @pytest.mark.parametrize("val", [3, 3.5])
+    def test_add_list_to_masked_array(self, val):
         # GH#22962
         ser = Series([1, None, 3], dtype="Int64")
         result = ser + [1, None, val]
-        expected = Series([2, None, 3 + val], dtype=dtype)
+        expected = Series([2, pd.NA, 3 + val], dtype=object)
         tm.assert_series_equal(result, expected)
 
         result = [1, None, val] + ser
@@ -357,7 +357,7 @@ def test_add_list_to_masked_array_boolean(self, request):
         msg = "operator is not supported by numexpr for the bool dtype"
         with tm.assert_produces_warning(warning, match=msg):
             result = ser + [True, None, True]
-        expected = Series([True, None, True], dtype="boolean")
+        expected = Series([2, pd.NA, 1], dtype=object)
         tm.assert_series_equal(result, expected)
 
         with tm.assert_produces_warning(warning, match=msg):