Polars: py-0.20.8 Release

🏆 Highlights

• Implemented tree formatting for LogicalPlan (#14221)

⚠️ Deprecations

• Deprecate positional args in pivot to prepare new functionality (#14428)

🚀 Performance improvements

• Combine small chunks in sinks for streaming pipelines (#14346)
• reduce heap allocs in expression/logical-plan iteration (#14440)
• simplify and speed up cum_sum and cum_prod (#14409)
• simplify negated predicates to improve row groups skipping (#14370)

✨ Enhancements

• Increase verbosity of duplicate column error message (#11899)
• change print to warn in reading csv from python file like object (#14469)
• Raise if pivot would introduce duplicate column names (#14431)
• apply negate in simplify expression pass (#14436)
• restrict more cloud interop to semaphore budget (#14435)
• Implement min/max for categorical dtype (#14112)
• Hide polars.testing.* in pytest stack traces (#14399)
• expose numpy view to integer types (#14405)
• Allow column name input in clip (#14410)
• add boolean rle decoding for parquet (#14403)
• Allow brackets in SQL join conditions (#14263)
• Implemented tree formatting for LogicalPlan (#14221)
• Implement mean_horizontal expression (#14369)
• support decimal comparison (#14338)
• Implements arr.shift (#14298)
• Implements list.n_unique (#14306)
• Do not panic when casting from an empty Series to pl.Decimal (#14330)
• unset WRITEABLE flag in zero-copy output (#14283)
• Support Categorical/Enum in Series.to_numpy (#14275)
• add parametric testing support for the Array dtype (#14265)

🐞 Bug fixes

• don't gc after variadic buffers are written (#14473)
• Increase verbosity of duplicate column error message (#11899)
• Return appropriate data type for duration mean and median (#14376)
• change print to warn in reading csv from python file like object (#14469)
• regression in out-of-core group-by by new string-type (#14464)
• DataFrame.pivot was returning incorrect results when multiple columns were passed to index and one of them was Struct (#14438)
• remove literal Series from projection state (#14437)
• pivot was producing incorrect results when (single) index was Struct (#14308)
• Error on some invalid clip inputs (#14416)
• Series.hist panicking on empty/all-null (#14407)
• rechunk series when apply_lambda (#14406)
• Raise if invalid strategy is passed to map_elements (#14397)
• Require exact checking for Decimals in assertion utils (#14357)
• fix ufunc for unlimited column args (#14328)
• Handle chunked Series in Series.to_numpy (#14341)
• Remove duplicated content in error messages (#8107)
• Fix set_operation if the input is sliced and be broadcast (#14303)
• Wrap par_iter in list.to_struct by POOL.install (#14304)
• Do not panic when casting from an empty Series to pl.Decimal (#14330)
• Preserve name when casting to Enum (#14320)
• list.get does not work on list of decimals (#14276)
• relax precision when up scaling (#14270)
• Allow format object series with registry (#14272)

📖 Documentation

• Update read_database docstring note about getting the connection URI string for sqlalchemy (#14461)
• Fix typo in plugins section (#14402)
• Add debugging section to contributing docs (#10576)
• Define what a 'character' means in slice / len_chars (#14395)
• Clarify behavior of DataFrame.rows_by_key (#14149)
• Fix some typos (#14394)
• Realign file structure of user guide (#14360)
• Rust examples for data structures in user guide (#14339)
• Add deprecation period policy example for post-1.0.0 (#14184)
• Add example for Series.bin.contains (#14297)
• Small clarifications in the contributing guide (#14310)
• Fix capitalization of user guide references (#14291)
• Fix explode docstring mentioning String types (#14285)
• Update deltalake docstrings to new link (#14282)

🛠️ Other improvements

• Ignore unclosed file warnings for now (#14467)
• Raise better error in import timings test (#14441)
• Refactor arg_min/max test case (#14439)
• Skip some OOC tests that fail randomly in the CI (#14434)
• Bump release drafter to v6 (#14429)
• Set specific temp dir for OOC tests (#14420)
• Bump setup-graphviz action to v2 (#14418)
• Minor test refactor (#14404)
• Update make clean command (#14408)
• Internal rename of _or to or_ in PyO3 (same for _xor/_and) (#14393)
• Minor refactor of DataFrame.to_numpy structured code (#14348)
• Update Series.to_numpy to handle Decimal/Time types in Rust (#14296)
• Add test for Series.to_numpy with timezones (#14337)
• Bump ruff version to 0.2.0 (#14294)
• Temporarily fix failing deltalake test (#14288)
• remove dataframe consortium standard api entrypoint (#14279)

Thank you to all our contributors for making this release possible! @BGR360, @CaselIT, @MarcoGorelli, @Migi, @NedJWestern, @Vincenthays, @alexander-beedie, @deanm0000, @dependabot, @dependabot[bot], @engdoreis, @flisky, @grinya007, @itamarst, @janosh, @kalekundert, @lukemanley, @mbuhidar, @mcrumiller, @petrosbar, @r-brink, @rben01, @reswqa, @ritchie46, @stinodego, @taki-mekhalfa and @thomasfrederikhoeck