PERF: avoid materializing values[indexer] in Block.setitem#64251
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jbrockmendel merged 10 commits intoApr 10, 2026
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ASV results for this change (same machine, same env): asv run -e -E existing -b SetitemObjectDtypeDatetimelike --record-samples --dry-runNote: for apples-to-apples comparison, baseline was measured by reverting only the optimization in
Geometric mean speedup:
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rhshadrach
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Feb 20, 2026
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Can you add a whatsnew for the perf improvement? otherwise LGTM |
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Added a whatsnew entry in |
jbrockmendel
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Mar 26, 2026
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thanks @hyoj0942 |
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Apr 12, 2026
…-comparison * upstream/main: PERF: use lookup instead of hash_inner_join for merge with unique right keys (pandas-dev#64691) BUG : update `SeriesGroupBy.ohlc()` to honor `as_index=False` (pandas-dev#65141) PERF: Use DataFrame-level reductions in DataFrame.agg with list of funcs (pandas-dev#65031) DOC: document required external libraries in read_* I/O docstrings (pandas-dev#65143) DOC: improve MultiIndex.is_monotonic_increasing/decreasing docstrings (pandas-dev#65154) BUG: Raise ValueError for non-boolean numeric_only in DataFrame/Series reductions (GH#53098) (pandas-dev#65131) BUG: Timedelta.round() raises ZeroDivisionError when internal unit is 's' and target frequency is sub-second (pandas-dev#64836) ENH: Add replace method to Index (closes pandas-dev#19495) (pandas-dev#65099) PERF: improve StringArray.isna (pandas-dev#57733) BUG: read parquet files with older pytz (DEP: keep lower pytz minimum version) (pandas-dev#65133) DEPR: deprecate dates-with-datetime64 in _maybe_downcast_for_indexing (pandas-dev#64871) DOC: note that DataFrame.values is not writeable (pandas-dev#65142) CLN: Update groupby observed defaults (pandas-dev#65148) PERF: avoid materializing values[indexer] in Block.setitem (pandas-dev#64251) DOC: update GroupBy.sum/min/max See Also sections (pandas-dev#65144)
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doc/source/whatsnew/vX.X.X.rstfile if fixing a bug or adding a new feature.AGENTS.md.This avoids materializing
values[indexer]in the object-dtype datetimelike compatibility path ofBlock.setitem.Changes:
length_of_indexerfor common indexer types instead of materializingvalues[indexer]len(values[indexer])whatsnewentry for the performance improvementValidation run locally:
python -m pytest pandas/tests/indexing/test_iloc.py -k "test_iloc_setitem_custom_object"python -m pre_commit run --files pandas/core/internals/blocks.pypython -m pre_commit run --files doc/source/whatsnew/v3.1.0.rst