diff --git a/doc/source/whatsnew/v0.23.1.txt b/doc/source/whatsnew/v0.23.1.txt
index 5a1bcce9b5970..3cebcc56e9083 100644
--- a/doc/source/whatsnew/v0.23.1.txt
+++ b/doc/source/whatsnew/v0.23.1.txt
@@ -10,12 +10,52 @@ and bug fixes. We recommend that all users upgrade to this version.
:local:
:backlinks: none
-
.. _whatsnew_0231.fixed_regressions:
Fixed Regressions
~~~~~~~~~~~~~~~~~
+**Comparing Series with datetime.date**
+
+We've reverted a 0.23.0 change to comparing a :class:`Series` holding datetimes and a ``datetime.date`` object (:issue:`21152`).
+In pandas 0.22 and earlier, comparing a Series holding datetimes and ``datetime.date`` objects would coerce the ``datetime.date`` to a datetime before comapring.
+This was inconsistent with Python, NumPy, and :class:`DatetimeIndex`, which never consider a datetime and ``datetime.date`` equal.
+
+In 0.23.0, we unified operations between DatetimeIndex and Series, and in the process changed comparisons between a Series of datetimes and ``datetime.date`` without warning.
+
+We've temporarily restored the 0.22.0 behavior, so datetimes and dates may again compare equal, but restore the 0.23.0 behavior in a future release.
+
+To summarize, here's the behavior in 0.22.0, 0.23.0, 0.23.1:
+
+.. code-block:: python
+
+ # 0.22.0... Silently coerce the datetime.date
+ >>> Series(pd.date_range('2017', periods=2)) == datetime.date(2017, 1, 1)
+ 0 True
+ 1 False
+ dtype: bool
+
+ # 0.23.0... Do not coerce the datetime.date
+ >>> Series(pd.date_range('2017', periods=2)) == datetime.date(2017, 1, 1)
+ 0 False
+ 1 False
+ dtype: bool
+
+ # 0.23.1... Coerce the datetime.date with a warning
+ >>> Series(pd.date_range('2017', periods=2)) == datetime.date(2017, 1, 1)
+ /bin/python:1: FutureWarning: Comparing Series of datetimes with 'datetime.date'. Currently, the
+ 'datetime.date' is coerced to a datetime. In the future pandas will
+ not coerce, and the values not compare equal to the 'datetime.date'.
+ To retain the current behavior, convert the 'datetime.date' to a
+ datetime with 'pd.Timestamp'.
+ #!/bin/python3
+ 0 True
+ 1 False
+ dtype: bool
+
+In addition, ordering comparisons will raise a ``TypeError`` in the future.
+
+**Other Fixes**
- Reverted the ability of :func:`~DataFrame.to_sql` to perform multivalue
inserts as this caused regression in certain cases (:issue:`21103`).
diff --git a/pandas/core/ops.py b/pandas/core/ops.py
index e14f82906cd06..540ebeee438f6 100644
--- a/pandas/core/ops.py
+++ b/pandas/core/ops.py
@@ -5,7 +5,10 @@
"""
# necessary to enforce truediv in Python 2.X
from __future__ import division
+import datetime
import operator
+import textwrap
+import warnings
import numpy as np
import pandas as pd
@@ -1197,8 +1200,35 @@ def wrapper(self, other, axis=None):
if is_datetime64_dtype(self) or is_datetime64tz_dtype(self):
# Dispatch to DatetimeIndex to ensure identical
# Series/Index behavior
+ if (isinstance(other, datetime.date) and
+ not isinstance(other, datetime.datetime)):
+ # https://github.com/pandas-dev/pandas/issues/21152
+ # Compatibility for difference between Series comparison w/
+ # datetime and date
+ msg = (
+ "Comparing Series of datetimes with 'datetime.date'. "
+ "Currently, the 'datetime.date' is coerced to a "
+ "datetime. In the future pandas will not coerce, "
+ "and {future}. "
+ "To retain the current behavior, "
+ "convert the 'datetime.date' to a datetime with "
+ "'pd.Timestamp'."
+ )
+
+ if op in {operator.lt, operator.le, operator.gt, operator.ge}:
+ future = "a TypeError will be raised"
+ else:
+ future = (
+ "'the values will not compare equal to the "
+ "'datetime.date'"
+ )
+ msg = '\n'.join(textwrap.wrap(msg.format(future=future)))
+ warnings.warn(msg, FutureWarning, stacklevel=2)
+ other = pd.Timestamp(other)
+
res_values = dispatch_to_index_op(op, self, other,
pd.DatetimeIndex)
+
return self._constructor(res_values, index=self.index,
name=res_name)
diff --git a/pandas/tests/series/test_arithmetic.py b/pandas/tests/series/test_arithmetic.py
index ec0d7296e540e..95836f046195a 100644
--- a/pandas/tests/series/test_arithmetic.py
+++ b/pandas/tests/series/test_arithmetic.py
@@ -88,6 +88,46 @@ def test_ser_cmp_result_names(self, names, op):
class TestTimestampSeriesComparison(object):
+ def test_dt64_ser_cmp_date_warning(self):
+ # https://github.com/pandas-dev/pandas/issues/21359
+ # Remove this test and enble invalid test below
+ ser = pd.Series(pd.date_range('20010101', periods=10), name='dates')
+ date = ser.iloc[0].to_pydatetime().date()
+
+ with tm.assert_produces_warning(FutureWarning) as m:
+ result = ser == date
+ expected = pd.Series([True] + [False] * 9, name='dates')
+ tm.assert_series_equal(result, expected)
+ assert "Comparing Series of datetimes " in str(m[0].message)
+ assert "will not compare equal" in str(m[0].message)
+
+ with tm.assert_produces_warning(FutureWarning) as m:
+ result = ser != date
+ tm.assert_series_equal(result, ~expected)
+ assert "will not compare equal" in str(m[0].message)
+
+ with tm.assert_produces_warning(FutureWarning) as m:
+ result = ser <= date
+ tm.assert_series_equal(result, expected)
+ assert "a TypeError will be raised" in str(m[0].message)
+
+ with tm.assert_produces_warning(FutureWarning) as m:
+ result = ser < date
+ tm.assert_series_equal(result, pd.Series([False] * 10, name='dates'))
+ assert "a TypeError will be raised" in str(m[0].message)
+
+ with tm.assert_produces_warning(FutureWarning) as m:
+ result = ser >= date
+ tm.assert_series_equal(result, pd.Series([True] * 10, name='dates'))
+ assert "a TypeError will be raised" in str(m[0].message)
+
+ with tm.assert_produces_warning(FutureWarning) as m:
+ result = ser > date
+ tm.assert_series_equal(result, pd.Series([False] + [True] * 9,
+ name='dates'))
+ assert "a TypeError will be raised" in str(m[0].message)
+
+ @pytest.mark.skip(reason="GH-21359")
def test_dt64ser_cmp_date_invalid(self):
# GH#19800 datetime.date comparison raises to
# match DatetimeIndex/Timestamp. This also matches the behavior