PERF: operate on arrays instead of Series in DataFrame/DataFrame ops (pandas-dev#33561)

Author: jorisvandenbossche

pandas/core/ops/__init__.py

@@ -262,15 +262,11 @@ def dispatch_to_series(left, right, func, axis=None):
     -------
     DataFrame
     """
-    # Note: we use iloc to access columns for compat with cases
-    #       with non-unique columns.
-    import pandas.core.computation.expressions as expressions
+    # Get the appropriate array-op to apply to each column/block's values.
+    array_op = get_array_op(func)
 
     right = lib.item_from_zerodim(right)
     if lib.is_scalar(right) or np.ndim(right) == 0:
-
-        # Get the appropriate array-op to apply to each block's values.
-        array_op = get_array_op(func)
         bm = left._mgr.apply(array_op, right=right)
         return type(left)(bm)
 
@@ -281,7 +277,6 @@ def dispatch_to_series(left, right, func, axis=None):
         #  fails in cases with empty columns reached via
         #  _frame_arith_method_with_reindex
 
-        array_op = get_array_op(func)
         bm = left._mgr.operate_blockwise(right._mgr, array_op)
         return type(left)(bm)
 
@@ -295,27 +290,24 @@ def dispatch_to_series(left, right, func, axis=None):
             # Note: we do not do this unconditionally as it may be lossy or
             #  expensive for EA dtypes.
             right = np.asarray(right)
-
-            def column_op(a, b):
-                return {i: func(a.iloc[:, i], b[i]) for i in range(len(a.columns))}
-
         else:
+            right = right._values
 
-            def column_op(a, b):
-                return {i: func(a.iloc[:, i], b.iloc[i]) for i in range(len(a.columns))}
+        arrays = [array_op(l, r) for l, r in zip(left._iter_column_arrays(), right)]
 
     elif isinstance(right, ABCSeries):
         assert right.index.equals(left.index)  # Handle other cases later
+        right = right._values
 
-        def column_op(a, b):
-            return {i: func(a.iloc[:, i], b) for i in range(len(a.columns))}
+        arrays = [array_op(l, right) for l in left._iter_column_arrays()]
 
     else:
         # Remaining cases have less-obvious dispatch rules
         raise NotImplementedError(right)
 
-    new_data = expressions.evaluate(column_op, left, right)
-    return new_data
+    return type(left)._from_arrays(
+        arrays, left.columns, left.index, verify_integrity=False
+    )
 
 
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