REF: simplify should_extension_dispatch, remove dispatch_to_extension_op (pandas-dev#32892)

Author: jbrockmendel

pandas/core/ops/__init__.py

@@ -3,18 +3,17 @@
 
 This is not a public API.
 """
-import datetime
 import operator
-from typing import TYPE_CHECKING, Optional, Set, Tuple
+from typing import TYPE_CHECKING, Optional, Set
 
 import numpy as np
 
-from pandas._libs import Timedelta, Timestamp, lib
+from pandas._libs import lib
 from pandas._libs.ops_dispatch import maybe_dispatch_ufunc_to_dunder_op  # noqa:F401
 from pandas._typing import ArrayLike, Level
 from pandas.util._decorators import Appender
 
-from pandas.core.dtypes.common import is_list_like, is_timedelta64_dtype
+from pandas.core.dtypes.common import is_list_like
 from pandas.core.dtypes.generic import ABCDataFrame, ABCIndexClass, ABCSeries
 from pandas.core.dtypes.missing import isna
 
@@ -152,65 +151,6 @@ def _maybe_match_name(a, b):
     return None
 
 
-def maybe_upcast_for_op(obj, shape: Tuple[int, ...]):
-    """
-    Cast non-pandas objects to pandas types to unify behavior of arithmetic
-    and comparison operations.
-
-    Parameters
-    ----------
-    obj: object
-    shape : tuple[int]
-
-    Returns
-    -------
-    out : object
-
-    Notes
-    -----
-    Be careful to call this *after* determining the `name` attribute to be
-    attached to the result of the arithmetic operation.
-    """
-    from pandas.core.arrays import DatetimeArray, TimedeltaArray
-
-    if type(obj) is datetime.timedelta:
-        # GH#22390  cast up to Timedelta to rely on Timedelta
-        # implementation; otherwise operation against numeric-dtype
-        # raises TypeError
-        return Timedelta(obj)
-    elif isinstance(obj, np.datetime64):
-        # GH#28080 numpy casts integer-dtype to datetime64 when doing
-        #  array[int] + datetime64, which we do not allow
-        if isna(obj):
-            # Avoid possible ambiguities with pd.NaT
-            obj = obj.astype("datetime64[ns]")
-            right = np.broadcast_to(obj, shape)
-            return DatetimeArray(right)
-
-        return Timestamp(obj)
-
-    elif isinstance(obj, np.timedelta64):
-        if isna(obj):
-            # wrapping timedelta64("NaT") in Timedelta returns NaT,
-            #  which would incorrectly be treated as a datetime-NaT, so
-            #  we broadcast and wrap in a TimedeltaArray
-            obj = obj.astype("timedelta64[ns]")
-            right = np.broadcast_to(obj, shape)
-            return TimedeltaArray(right)
-
-        # In particular non-nanosecond timedelta64 needs to be cast to
-        #  nanoseconds, or else we get undesired behavior like
-        #  np.timedelta64(3, 'D') / 2 == np.timedelta64(1, 'D')
-        return Timedelta(obj)
-
-    elif isinstance(obj, np.ndarray) and is_timedelta64_dtype(obj.dtype):
-        # GH#22390 Unfortunately we need to special-case right-hand
-        # timedelta64 dtypes because numpy casts integer dtypes to
-        # timedelta64 when operating with timedelta64
-        return TimedeltaArray._from_sequence(obj)
-    return obj
-
-
 # -----------------------------------------------------------------------------
 
 

pandas/core/ops/array_ops.py

@@ -2,9 +2,10 @@
 Functions for arithmetic and comparison operations on NumPy arrays and
 ExtensionArrays.
 """
+from datetime import timedelta
 from functools import partial
 import operator
-from typing import Any, Optional
+from typing import Any, Optional, Tuple
 
 import numpy as np
 
@@ -24,17 +25,11 @@
     is_object_dtype,
     is_scalar,
 )
-from pandas.core.dtypes.generic import (
-    ABCDatetimeArray,
-    ABCExtensionArray,
-    ABCIndex,
-    ABCSeries,
-    ABCTimedeltaArray,
-)
+from pandas.core.dtypes.generic import ABCExtensionArray, ABCIndex, ABCSeries
 from pandas.core.dtypes.missing import isna, notna
 
 from pandas.core.ops import missing
-from pandas.core.ops.dispatch import dispatch_to_extension_op, should_extension_dispatch
+from pandas.core.ops.dispatch import should_extension_dispatch
 from pandas.core.ops.invalid import invalid_comparison
 from pandas.core.ops.roperator import rpow
 
@@ -199,23 +194,15 @@ def arithmetic_op(left: ArrayLike, right: Any, op, str_rep: str):
     ndarrray or ExtensionArray
         Or a 2-tuple of these in the case of divmod or rdivmod.
     """
-    from pandas.core.ops import maybe_upcast_for_op
 
     # NB: We assume that extract_array has already been called
     #  on `left` and `right`.
-    lvalues = left
-    rvalues = right
+    lvalues = maybe_upcast_datetimelike_array(left)
+    rvalues = maybe_upcast_for_op(right, lvalues.shape)
 
-    rvalues = maybe_upcast_for_op(rvalues, lvalues.shape)
-
-    if should_extension_dispatch(left, rvalues) or isinstance(
-        rvalues, (ABCTimedeltaArray, ABCDatetimeArray, Timestamp, Timedelta)
-    ):
-        # TimedeltaArray, DatetimeArray, and Timestamp are included here
-        #  because they have `freq` attribute which is handled correctly
-        #  by dispatch_to_extension_op.
+    if should_extension_dispatch(lvalues, rvalues) or isinstance(rvalues, Timedelta):
         # Timedelta is included because numexpr will fail on it, see GH#31457
-        res_values = dispatch_to_extension_op(op, lvalues, rvalues)
+        res_values = op(lvalues, rvalues)
 
     else:
         with np.errstate(all="ignore"):
@@ -287,7 +274,7 @@ def comparison_op(
     ndarray or ExtensionArray
     """
     # NB: We assume extract_array has already been called on left and right
-    lvalues = left
+    lvalues = maybe_upcast_datetimelike_array(left)
     rvalues = right
 
     rvalues = lib.item_from_zerodim(rvalues)
@@ -307,7 +294,8 @@ def comparison_op(
             )
 
     if should_extension_dispatch(lvalues, rvalues):
-        res_values = dispatch_to_extension_op(op, lvalues, rvalues)
+        # Call the method on lvalues
+        res_values = op(lvalues, rvalues)
 
     elif is_scalar(rvalues) and isna(rvalues):
         # numpy does not like comparisons vs None
@@ -406,11 +394,12 @@ def fill_bool(x, left=None):
         right = construct_1d_object_array_from_listlike(right)
 
     # NB: We assume extract_array has already been called on left and right
-    lvalues = left
+    lvalues = maybe_upcast_datetimelike_array(left)
     rvalues = right
 
     if should_extension_dispatch(lvalues, rvalues):
-        res_values = dispatch_to_extension_op(op, lvalues, rvalues)
+        # Call the method on lvalues
+        res_values = op(lvalues, rvalues)
 
     else:
         if isinstance(rvalues, np.ndarray):
@@ -453,3 +442,87 @@ def get_array_op(op, str_rep: Optional[str] = None):
         return partial(logical_op, op=op)
     else:
         return partial(arithmetic_op, op=op, str_rep=str_rep)
+
+
+def maybe_upcast_datetimelike_array(obj: ArrayLike) -> ArrayLike:
+    """
+    If we have an ndarray that is either datetime64 or timedelta64, wrap in EA.
+
+    Parameters
+    ----------
+    obj : ndarray or ExtensionArray
+
+    Returns
+    -------
+    ndarray or ExtensionArray
+    """
+    if isinstance(obj, np.ndarray):
+        if obj.dtype.kind == "m":
+            from pandas.core.arrays import TimedeltaArray
+
+            return TimedeltaArray._from_sequence(obj)
+        if obj.dtype.kind == "M":
+            from pandas.core.arrays import DatetimeArray
+
+            return DatetimeArray._from_sequence(obj)
+
+    return obj
+
+
+def maybe_upcast_for_op(obj, shape: Tuple[int, ...]):
+    """
+    Cast non-pandas objects to pandas types to unify behavior of arithmetic
+    and comparison operations.
+
+    Parameters
+    ----------
+    obj: object
+    shape : tuple[int]
+
+    Returns
+    -------
+    out : object
+
+    Notes
+    -----
+    Be careful to call this *after* determining the `name` attribute to be
+    attached to the result of the arithmetic operation.
+    """
+    from pandas.core.arrays import DatetimeArray, TimedeltaArray
+
+    if type(obj) is timedelta:
+        # GH#22390  cast up to Timedelta to rely on Timedelta
+        # implementation; otherwise operation against numeric-dtype
+        # raises TypeError
+        return Timedelta(obj)
+    elif isinstance(obj, np.datetime64):
+        # GH#28080 numpy casts integer-dtype to datetime64 when doing
+        #  array[int] + datetime64, which we do not allow
+        if isna(obj):
+            # Avoid possible ambiguities with pd.NaT
+            obj = obj.astype("datetime64[ns]")
+            right = np.broadcast_to(obj, shape)
+            return DatetimeArray(right)
+
+        return Timestamp(obj)
+
+    elif isinstance(obj, np.timedelta64):
+        if isna(obj):
+            # wrapping timedelta64("NaT") in Timedelta returns NaT,
+            #  which would incorrectly be treated as a datetime-NaT, so
+            #  we broadcast and wrap in a TimedeltaArray
+            obj = obj.astype("timedelta64[ns]")
+            right = np.broadcast_to(obj, shape)
+            return TimedeltaArray(right)
+
+        # In particular non-nanosecond timedelta64 needs to be cast to
+        #  nanoseconds, or else we get undesired behavior like
+        #  np.timedelta64(3, 'D') / 2 == np.timedelta64(1, 'D')
+        return Timedelta(obj)
+
+    elif isinstance(obj, np.ndarray) and obj.dtype.kind == "m":
+        # GH#22390 Unfortunately we need to special-case right-hand
+        # timedelta64 dtypes because numpy casts integer dtypes to
+        # timedelta64 when operating with timedelta64
+        return TimedeltaArray._from_sequence(obj)
+    return obj

pandas/core/ops/dispatch.py

@@ -3,48 +3,31 @@
 """
 from typing import Any
 
-import numpy as np
-
 from pandas._typing import ArrayLike
 
 from pandas.core.dtypes.common import (
     is_datetime64_dtype,
-    is_extension_array_dtype,
     is_integer_dtype,
     is_object_dtype,
-    is_scalar,
     is_timedelta64_dtype,
 )
-from pandas.core.dtypes.generic import ABCSeries
-
-from pandas.core.construction import array
+from pandas.core.dtypes.generic import ABCExtensionArray
 
 
-def should_extension_dispatch(left: ABCSeries, right: Any) -> bool:
+def should_extension_dispatch(left: ArrayLike, right: Any) -> bool:
     """
-    Identify cases where Series operation should use dispatch_to_extension_op.
+    Identify cases where Series operation should dispatch to ExtensionArray method.
 
     Parameters
     ----------
-    left : Series
+    left : np.ndarray or ExtensionArray
     right : object
 
     Returns
     -------
     bool
     """
-    if (
-        is_extension_array_dtype(left.dtype)
-        or is_datetime64_dtype(left.dtype)
-        or is_timedelta64_dtype(left.dtype)
-    ):
-        return True
-
-    if not is_scalar(right) and is_extension_array_dtype(right):
-        # GH#22378 disallow scalar to exclude e.g. "category", "Int64"
-        return True
-
-    return False
+    return isinstance(left, ABCExtensionArray) or isinstance(right, ABCExtensionArray)
 
 
 def should_series_dispatch(left, right, op):
@@ -93,34 +76,3 @@ def should_series_dispatch(left, right, op):
         return True
 
     return False
-
-
-def dispatch_to_extension_op(op, left: ArrayLike, right: Any):
-    """
-    Assume that left or right is a Series backed by an ExtensionArray,
-    apply the operator defined by op.
-
-    Parameters
-    ----------
-    op : binary operator
-    left : ExtensionArray or np.ndarray
-    right : object
-
-    Returns
-    -------
-    ExtensionArray or np.ndarray
-        2-tuple of these if op is divmod or rdivmod
-    """
-    # NB: left and right should already be unboxed, so neither should be
-    #  a Series or Index.
-
-    if left.dtype.kind in "mM" and isinstance(left, np.ndarray):
-        # We need to cast datetime64 and timedelta64 ndarrays to
-        #  DatetimeArray/TimedeltaArray.  But we avoid wrapping others in
-        #  PandasArray as that behaves poorly with e.g. IntegerArray.
-        left = array(left)
-
-    # The op calls will raise TypeError if the op is not defined
-    # on the ExtensionArray
-    res_values = op(left, right)
-    return res_values