REF: prepare (upcast) scalar before dispatching to arithmetic array ops

pandas/core/arrays/numpy_.py

@@ -394,6 +394,7 @@ def _cmp_method(self, other, op):
         if isinstance(other, PandasArray):
             other = other._ndarray
 
+        other = ops.prepare_scalar_for_op(other, (len(self),))
         pd_op = ops.get_array_op(op)
         with np.errstate(all="ignore"):
             result = pd_op(self._ndarray, other)

pandas/core/frame.py

@@ -6801,6 +6801,7 @@ def _arith_method(self, other, op):
             return ops.frame_arith_method_with_reindex(self, other, op)
 
         axis = 1  # only relevant for Series other case
+        other = ops.prepare_scalar_for_op(other, (self.shape[axis],))
 
         self, other = ops.align_method_FRAME(self, other, axis, flex=True, level=None)
 

pandas/core/ops/__init__.py

@@ -35,6 +35,7 @@
     comparison_op,
     get_array_op,
     logical_op,
+    prepare_scalar_for_op,
 )
 from pandas.core.ops.common import (  # noqa:F401
     get_op_result_name,
@@ -428,6 +429,7 @@ def f(self, other, axis=default_axis, level=None, fill_value=None):
 
         axis = self._get_axis_number(axis) if axis is not None else 1
 
+        other = prepare_scalar_for_op(other, (self.shape[axis],))
         self, other = align_method_FRAME(self, other, axis, flex=True, level=level)
 
         if isinstance(other, ABCDataFrame):

pandas/core/ops/array_ops.py

@@ -196,12 +196,12 @@ def arithmetic_op(left: ArrayLike, right: Any, op):
     """
 
     # NB: We assume that extract_array has already been called
-    #  on `left` and `right`.
+    #  on `left` and `right`,
+    #  and `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)
     lvalues = ensure_wrapped_if_datetimelike(left)
     rvalues = ensure_wrapped_if_datetimelike(right)
-    rvalues = _maybe_upcast_for_op(rvalues, lvalues.shape)
 
     if should_extension_dispatch(lvalues, rvalues) or isinstance(rvalues, Timedelta):
         # Timedelta is included because numexpr will fail on it, see GH#31457
@@ -422,7 +422,7 @@ def get_array_op(op):
         raise NotImplementedError(op_name)
 
 
-def _maybe_upcast_for_op(obj, shape: Shape):
+def prepare_scalar_for_op(obj, shape: Shape):
     """
     Cast non-pandas objects to pandas types to unify behavior of arithmetic
     and comparison operations.

pandas/core/series.py

@@ -5313,6 +5313,7 @@ def _arith_method(self, other, op):
 
         lvalues = self._values
         rvalues = extract_array(other, extract_numpy=True, extract_range=True)
+        rvalues = ops.prepare_scalar_for_op(rvalues, lvalues.shape)
 
         with np.errstate(all="ignore"):
             result = ops.arithmetic_op(lvalues, rvalues, op)