issues: 2279042264

This data as json

id node_id number title user state locked assignee milestone comments created_at updated_at closed_at author_association active_lock_reason draft pull_request body reactions performed_via_github_app state_reason repo type
2279042264 PR_kwDOAMm_X85ui13E 8999 Port negative frequency fix for `pandas.date_range` to `cftime_range` 6628425 open 0     0 2024-05-04T14:48:08Z 2024-05-04T14:51:26Z   MEMBER   0 pydata/xarray/pulls/8999

Like pandas.date_range, cftime_range would previously return dates outside the range of the specified start and end dates if provided a negative frequency: ```

start = cftime.DatetimeGregorian(2023, 10, 31) end = cftime.DatetimeGregorian(2021, 11, 1) xr.cftime_range(start, end, freq="-1YE") CFTimeIndex([2023-12-31 00:00:00, 2022-12-31 00:00:00, 2021-12-31 00:00:00], dtype='object', length=3, calendar='standard', freq='-1YE-DEC') ```

This PR ports a bug fix from pandas (https://github.com/pandas-dev/pandas/issues/56147) to prevent this from happening. The above example now produces: ```

start = cftime.DatetimeGregorian(2023, 10, 31) end = cftime.DatetimeGregorian(2021, 11, 1) xr.cftime_range(start, end, freq="-1YE") CFTimeIndex([2022-12-31 00:00:00, 2021-12-31 00:00:00], dtype='object', length=2, calendar='standard', freq=None) ```

Since this is a bug fix, we do not make any attempt to preserve the old behavior if an earlier version of pandas is installed. In the testing context this means we skip some tests for pandas versions less than 3.0.

  • [x] User visible changes (including notable bug fixes) are documented in whats-new.rst
 
{
    "url": "https://api.github.com/repos/pydata/xarray/issues/8999/reactions",
    "total_count": 1,
    "+1": 1,
    "-1": 0,
    "laugh": 0,
    "hooray": 0,
    "confused": 0,
    "heart": 0,
    "rocket": 0,
    "eyes": 0
}
     13221727 pull

Links from other tables