feat(expr-ir): Add {DataFrame,Series}.explode(empty_as_nulls, keep_nulls)#3347
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dangotbanned merged 21 commits intoexpr-ir/plz-finish-arrow-exprfrom Dec 9, 2025
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feat(expr-ir): Add {DataFrame,Series}.explode(empty_as_nulls, keep_nulls)#3347dangotbanned merged 21 commits intoexpr-ir/plz-finish-arrow-exprfrom
{DataFrame,Series}.explode(empty_as_nulls, keep_nulls)#3347dangotbanned merged 21 commits intoexpr-ir/plz-finish-arrow-exprfrom
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One `collect_schema()` is now shared for selector expansion & type checking
Mentioned in (#1644 (comment)) Multi-column coming up next 😄
Its enough to pass the test suite, but next up is refactoring `_table_explode_2` to handle everything >=2
Pretty sure the `AttributeError` is unrelated to this, but nice to have found
The 3 passing tests are a coincidence, since they're supposed to be equivalent to the default
dangotbanned
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Dec 9, 2025
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Also makes it clearer which cases are related in an IDE
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Description
Discovered a way to do
ArrowDataFrame.explode, while staying vectorized.Additionally, (https://github.com/pola-rs/polars/releases/tag/py-1.36.0) just added some options which allow some optimizations - so I've implemented those as well 😏
This is particularly helpful for
pyarrow, asexplode(empty_as_nulls=False, keep_nulls=False)is what happens natively if we don't get in the way.Note
I've split this out from (#3325) to make it easier to upstream if wanted
50% of the LOC is in (https://github.com/narwhals-dev/narwhals/blob/e86c66dd5976fdbf24b68eff58bd4878b909d227/tests/plan/explode_test.py)
Related issues
ArrowExpr#3325ArrowDataFrame.explode#1644 (comment)ArrowDataFrame.explode#1644 (comment)Series[list].explode()should not returnNonefor empty lists pola-rs/polars#17664empty_as_nullandkeep_nullsflags toExpr.explodepola-rs/polars#25289empty_as_nullandkeep_nullsto{Lazy,Data}Frame.explodepola-rs/polars#25369Checklist