CLN: streamline Series _construct_result calls (#28637)

Author: jbrockmendel

pandas/core/ops/__init__.py

@@ -5,15 +5,20 @@
 """
 import datetime
 import operator
-from typing import Tuple
+from typing import Tuple, Union
 
 import numpy as np
 
 from pandas._libs import Timedelta, Timestamp, lib
 from pandas.util._decorators import Appender
 
 from pandas.core.dtypes.common import is_list_like, is_timedelta64_dtype
-from pandas.core.dtypes.generic import ABCDataFrame, ABCIndexClass, ABCSeries
+from pandas.core.dtypes.generic import (
+    ABCDataFrame,
+    ABCExtensionArray,
+    ABCIndexClass,
+    ABCSeries,
+)
 from pandas.core.dtypes.missing import isna
 
 from pandas.core.construction import extract_array
@@ -436,13 +441,37 @@ def _align_method_SERIES(left, right, align_asobject=False):
     return left, right
 
 
-def _construct_result(left, result, index, name, dtype=None):
+def _construct_result(
+    left: ABCSeries,
+    result: Union[np.ndarray, ABCExtensionArray],
+    index: ABCIndexClass,
+    name,
+):
     """
-    If the raw op result has a non-None name (e.g. it is an Index object) and
-    the name argument is None, then passing name to the constructor will
-    not be enough; we still need to override the name attribute.
+    Construct an appropriately-labelled Series from the result of an op.
+
+    Parameters
+    ----------
+    left : Series
+    result : ndarray or ExtensionArray
+    index : Index
+    name : object
+
+    Returns
+    -------
+    Series
+        In the case of __divmod__ or __rdivmod__, a 2-tuple of Series.
     """
-    out = left._constructor(result, index=index, dtype=dtype)
+    if isinstance(result, tuple):
+        # produced by divmod or rdivmod
+        return (
+            _construct_result(left, result[0], index=index, name=name),
+            _construct_result(left, result[1], index=index, name=name),
+        )
+
+    # We do not pass dtype to ensure that the Series constructor
+    #  does inference in the case where `result` has object-dtype.
+    out = left._constructor(result, index=index)
     out = out.__finalize__(left)
 
     # Set the result's name after __finalize__ is called because __finalize__
@@ -451,15 +480,6 @@ def _construct_result(left, result, index, name, dtype=None):
     return out
 
 
-def _construct_divmod_result(left, result, index, name, dtype=None):
-    """divmod returns a tuple of like indexed series instead of a single series.
-    """
-    return (
-        _construct_result(left, result[0], index=index, name=name, dtype=dtype),
-        _construct_result(left, result[1], index=index, name=name, dtype=dtype),
-    )
-
-
 def _arith_method_SERIES(cls, op, special):
     """
     Wrapper function for Series arithmetic operations, to avoid
@@ -468,9 +488,6 @@ def _arith_method_SERIES(cls, op, special):
     str_rep = _get_opstr(op)
     op_name = _get_op_name(op, special)
     eval_kwargs = _gen_eval_kwargs(op_name)
-    construct_result = (
-        _construct_divmod_result if op in [divmod, rdivmod] else _construct_result
-    )
 
     def wrapper(left, right):
         if isinstance(right, ABCDataFrame):
@@ -482,9 +499,7 @@ def wrapper(left, right):
         lvalues = extract_array(left, extract_numpy=True)
         result = arithmetic_op(lvalues, right, op, str_rep, eval_kwargs)
 
-        # We do not pass dtype to ensure that the Series constructor
-        #  does inference in the case where `result` has object-dtype.
-        return construct_result(left, result, index=left.index, name=res_name)
+        return _construct_result(left, result, index=left.index, name=res_name)
 
     wrapper.__name__ = op_name
     return wrapper
@@ -553,6 +568,7 @@ def flex_wrapper(self, other, level=None, fill_value=None, axis=0):
         # validate axis
         if axis is not None:
             self._get_axis_number(axis)
+
         if isinstance(other, ABCSeries):
             return self._binop(other, op, level=level, fill_value=fill_value)
         elif isinstance(other, (np.ndarray, list, tuple)):
@@ -564,7 +580,7 @@ def flex_wrapper(self, other, level=None, fill_value=None, axis=0):
             if fill_value is not None:
                 self = self.fillna(fill_value)
 
-            return self._constructor(op(self, other), self.index).__finalize__(self)
+            return op(self, other)
 
     flex_wrapper.__name__ = name
     return flex_wrapper

pandas/core/series.py

@@ -2738,10 +2738,7 @@ def _binop(self, other, func, level=None, fill_value=None):
             result = func(this_vals, other_vals)
 
         name = ops.get_op_result_name(self, other)
-        if func.__name__ in ["divmod", "rdivmod"]:
-            ret = ops._construct_divmod_result(self, result, new_index, name)
-        else:
-            ret = ops._construct_result(self, result, new_index, name)
+        ret = ops._construct_result(self, result, new_index, name)
         return ret
 
     def combine(self, other, func, fill_value=None):