DEPR: groupby with duplicate index level names#64721
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jbrockmendel wants to merge 4 commits intopandas-dev:mainfrom
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DEPR: groupby with duplicate index level names#64721jbrockmendel wants to merge 4 commits intopandas-dev:mainfrom
jbrockmendel wants to merge 4 commits intopandas-dev:mainfrom
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…ions Replace kh_get + kh_put patterns with kh_put alone (checking ret for new-vs-existing), removing a redundant hash computation and probe per element in value_count, _unique, duplicated(keep=False), and get_labels_groupby. Also clean up the vendored khash.h: - Remove dead deletion-tracking code from kh_put/kh_get (deletions are disabled via __ac_isdel=0, but site variable and branches remained) - Fix kh_clear to use 0xff (all-empty) instead of 0xaa, which was a leftover from the original 2-bit-per-slot flag scheme - Remove unreachable shrink path from kh_put resize trigger - Fix value_count object pre-sizing from n//10 to n Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Deprecate grouping by an index level name when the name matches multiple levels of a MultiIndex. The current behavior silently uses the first matching level, which is ambiguous. In a future version this will raise a ValueError. closes pandas-dev#49434 Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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Summary
MultiIndex. Currently the first matching level is silently used, which is ambiguous. In a future version this will raiseValueError.Pandas4WarninginGrouping._ilevelwhen a level name occurs more than once in aMultiIndex.closes #49434
Test plan
test_groupby_duplicate_index_level_namespasses🤖 Generated with Claude Code