• ClosesSupportdrop_incomplete kwarg withSeasonGrouper #10426
• Tests added
• User visible changes (including notable bug fixes) are documented inwhats-new.rst
• New functions/methods are listed inapi.rst

SeasonGrouper Enhancements

Enhanced theSeasonGrouper class to support conditional omission of incomplete seasons—now aligned with behavior inSeasonResampler.

Summary of Changes

1.drop_incomplete Keyword Argument

• Introduced a new boolean parameterdrop_incomplete, defaulting toFalse for backward compatibility.
• Enables users to choose whether incomplete seasons should be excluded during grouping.

2. Revisedfactorize Method

• Core logic for dropping incomplete seasons has been moved into thefactorize method.
• Whendrop_incomplete=True, it:
  • Iterates over each year-series chunk.
  • Verifies that all expected months in the season are present.
  • Excludes any data for that season-year pair if months are missing.

3. Updatedreset Method

• Ensures that thedrop_incomplete setting correctly propagates when resetting or re-initializing the grouper.