Skip to content

BUG: DatetimeIndex intersection with non-anchored freq #62341

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
wants to merge 4 commits into
base: main
Choose a base branch
from
Open

BUG: DatetimeIndex intersection with non-anchored freq #62341

Show file tree
Hide file tree
Changes from 1 commit
Commits
Show all changes
4 commits
Select commit Hold shift + click to select a range
1c545b9
Updated condition and added test
arthurlw Sep 14, 2025
8265c7d
Updated condition logic
arthurlw Oct 18, 2025
526bcc6
add comment back
arthurlw Oct 18, 2025
7cee449
add removed test condition
arthurlw Oct 18, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
2 changes: 1 addition & 1 deletion pandas/core/indexes/datetimelike.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -627,7 +627,7 @@ def _fast_intersect(self, other, sort):

def _can_fast_intersect(self, other: Self) -> bool:
# Note: we only get here with len(self) > 0 and len(other) > 0
if self.freq is None:
if self.freq is None or self.freq == "C":
return False

elif other.freq != self.freq:
Expand Down
15 changes: 14 additions & 1 deletion pandas/tests/indexes/datetimes/test_setops.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,7 @@
import numpy as np
import pytest

from pandas._libs.tslibs.timedeltas import Timedelta
import pandas.util._test_decorators as td

import pandas as pd
Expand Down Expand Up @@ -709,7 +710,6 @@ def test_intersection_bug(self):
b = bdate_range("12/10/2011", "12/20/2011", freq="C")
result = a.intersection(b)
tm.assert_index_equal(result, b)
assert result.freq == b.freq

@pytest.mark.parametrize(
"tz", [None, "UTC", "Europe/Berlin", timezone(timedelta(hours=-1))]
Expand Down Expand Up @@ -757,3 +757,16 @@ def test_intersection_non_nano_rangelike():
freq="D",
)
tm.assert_index_equal(result, expected)


def test_cday_intersection_empty():
# GH#44025
off = pd.offsets.CDay(1, normalize=False)
ts = Timestamp("2021-10-13 09:00")
ts2 = ts + Timedelta("1 hour")

dti1 = date_range(start=ts, periods=10, freq=off)
dti2 = date_range(start=ts2, periods=10, freq=off)
result = dti1.intersection(dti2)
expected = DatetimeIndex([], dtype="datetime64[ns]")
tm.assert_index_equal(result, expected)
Loading