From 9105713ad0e8c859a9f1e91e80c54daad5fb9172 Mon Sep 17 00:00:00 2001
From: jbrockmendel <jbrockmendel@gmail.com>
Date: Thu, 12 Sep 2019 08:11:46 -0700
Subject: [PATCH] REF: prepare Series arith op to be refactored to array op

---
 pandas/core/ops/__init__.py  | 16 ++++++------
 pandas/core/ops/array_ops.py | 48 ++++++++++++++++++++----------------
 2 files changed, 36 insertions(+), 28 deletions(-)

diff --git a/pandas/core/ops/__init__.py b/pandas/core/ops/__init__.py
index 90fb3b8685c93..baa978c32b2c3 100644
--- a/pandas/core/ops/__init__.py
+++ b/pandas/core/ops/__init__.py
@@ -40,7 +40,11 @@
 
 from pandas._typing import ArrayLike
 from pandas.core.construction import array, extract_array
-from pandas.core.ops.array_ops import comp_method_OBJECT_ARRAY, define_na_arithmetic_op
+from pandas.core.ops.array_ops import (
+    comp_method_OBJECT_ARRAY,
+    define_na_arithmetic_op,
+    na_arithmetic_op,
+)
 from pandas.core.ops.docstrings import (
     _arith_doc_FRAME,
     _flex_comp_doc_FRAME,
@@ -616,20 +620,18 @@ def _arith_method_SERIES(cls, op, special):
         _construct_divmod_result if op in [divmod, rdivmod] else _construct_result
     )
 
-    na_op = define_na_arithmetic_op(op, str_rep, eval_kwargs)
-
     def wrapper(left, right):
         if isinstance(right, ABCDataFrame):
             return NotImplemented
 
+        left, right = _align_method_SERIES(left, right)
+        res_name = get_op_result_name(left, right)
+
         keep_null_freq = isinstance(
             right,
             (ABCDatetimeIndex, ABCDatetimeArray, ABCTimedeltaIndex, ABCTimedeltaArray),
         )
 
-        left, right = _align_method_SERIES(left, right)
-        res_name = get_op_result_name(left, right)
-
         lvalues = extract_array(left, extract_numpy=True)
         rvalues = extract_array(right, extract_numpy=True)
 
@@ -646,7 +648,7 @@ def wrapper(left, right):
 
         else:
             with np.errstate(all="ignore"):
-                result = na_op(lvalues, rvalues)
+                result = na_arithmetic_op(lvalues, rvalues, 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.
diff --git a/pandas/core/ops/array_ops.py b/pandas/core/ops/array_ops.py
index f5f6d77676f1f..d8b00bc629d44 100644
--- a/pandas/core/ops/array_ops.py
+++ b/pandas/core/ops/array_ops.py
@@ -98,31 +98,37 @@ def masked_arith_op(x, y, op):
 
 def define_na_arithmetic_op(op, str_rep, eval_kwargs):
     def na_op(x, y):
-        """
-        Return the result of evaluating op on the passed in values.
+        return na_arithmetic_op(x, y, op, str_rep, eval_kwargs)
 
-        If native types are not compatible, try coersion to object dtype.
+    return na_op
 
-        Parameters
-        ----------
-        x : array-like
-        y : array-like or scalar
 
-        Returns
-        -------
-        array-like
+def na_arithmetic_op(left, right, op, str_rep, eval_kwargs):
+    """
+    Return the result of evaluating op on the passed in values.
 
-        Raises
-        ------
-        TypeError : invalid operation
-        """
-        import pandas.core.computation.expressions as expressions
+    If native types are not compatible, try coersion to object dtype.
 
-        try:
-            result = expressions.evaluate(op, str_rep, x, y, **eval_kwargs)
-        except TypeError:
-            result = masked_arith_op(x, y, op)
+    Parameters
+    ----------
+    left : np.ndarray
+    right : np.ndarray or scalar
+    str_rep : str or None
+    eval_kwargs : kwargs to pass to expressions
+
+    Returns
+    -------
+    array-like
+
+    Raises
+    ------
+    TypeError : invalid operation
+    """
+    import pandas.core.computation.expressions as expressions
 
-        return missing.dispatch_fill_zeros(op, x, y, result)
+    try:
+        result = expressions.evaluate(op, str_rep, left, right, **eval_kwargs)
+    except TypeError:
+        result = masked_arith_op(left, right, op)
 
-    return na_op
+    return missing.dispatch_fill_zeros(op, left, right, result)