Python Polars 1.0.0-rc.1

💥 Breaking changes

• Make hive_partitioning parameter default to None, which is automatically enabled for single directory inputs, and disabled otherwise (#17106)
• Split replace functionality into two separate functions (#16921)
• Default to writing binview data to IPC (#17084)
• Do not parse hive partitions from user provided directory/glob path (#17055)
• Remove re-export of type aliases (#17032)
• Add strict parameter to DataFrame/LazyFrame.drop and fix behavior to default to True (#17044)
• Rename ModuleUpgradeRequired and PolarsPanicError error, remove InvalidAssert error (#17033)
• Change data orientation inference logic for DataFrame construction and warn when row orientation is inferred (#16976)
• Properly apply strict parameter in Series constructor (#16939)
• Remove supertype definition of List and non-List types (#16918)
• Consistently convert to given time zone in Series constructor (#16828)
• Update reshape to return Array types instead of List types (#16825)
• Default to raising on out-of-bounds indices in all get/gather operations (#16841)
• Native selector XOR set operation, guarantee consistent selector column-order (#16833)
• Set infer_schema_length as keyword-only argument in str.json_decode (#16835)
• Update set_sorted to only accept a single column (#16800)
• Remove deprecated parameters in Series.cut/qcut and update struct field names (#16741)
• Expedited removal of certain deprecated functionality (#16754)
• Update some error types to more appropriate variants (#15030)
• Scheduled removal of deprecated functionality (#16715)
• Change default offset in group_by_dynamic from 'negative every' to 'zero' (#16658)
• Constrain access to globals from DataFrame.sql in favor of top-level pl.sql (#16598)
• Read 2D NumPy arrays as Array type instead of List (#16710)
• Update clip to no longer propagate nulls in the given bounds (#14413)
• Change str.to_datetime to default to microsecond precision for format specifiers "%f" and "%.f" (#13597)
• Update resulting column names in pivot when pivoting by multiple values (#16439)
• Preserve nulls in ewm_mean, ewm_std, and ewm_var (#15503)
• Restrict casting for temporal data types (#14142)
• Support Decimal types by default when converting from Arrow (#15324)
• Remove serde functionality from pl.read_json and DataFrame.write_json (#16550)
• Update function signature of nth to allow positional input of indices, remove columns parameter (#16510)
• Rename struct fields of rle output to len/value and update data type of len field (#15249)
• Remove class variables from some DataTypes (#16524)
• Add check_names parameter to Series.equals and default to False (#16610)

⚠️ Deprecations

• Deprecate size parameter in parametric testing strategies in favor of min_size/max_size (#17128)
• Split replace functionality into two separate functions (#16921)
• Rename DataFrame.melt to unpivot and make parameters consistent with pivot (#17095)
• Remove re-export of exceptions at top-level (#17059)
• Deprecate dt.mean/dt.median in favor of mean/median (#16888)
• Deprecate LazyFrame.with_context in favor of horizontal concatenation (#16860)
• Rename parameter descending to reverse in top_k methods (#16817)
• Rename str.concat to str.join and update default delimiter (#16790)
• Deprecate arctan2d in favor of arctan2(...).degrees() (#16786)

🚀 Performance improvements

• Default to writing binview data to IPC (#17084)
• Parallelize arrow conversion if binview -> large_bin (#17083)
• GC buffers in if_then_else view kernel (#16993)
• Desugar AND filter into multiple nodes (#16992)
• Optimize generic argsort of row-encoding (#16894)
• Improve rle_id iteration perf and set sorted flags (#16893)
• Optimize string/binary sort (#16871)
• Use split_at in split (#16865)
• Use split_at instead of double slice in chunk splits. (#16856)
• Don't rechunk in align_ if arrays are aligned (#16850)
• Don't create small chunks in parallel collect. (#16845)
• Add dedicated no-null branch in arg_sort (#16808)
• Speed up dt.offset_by 2x for constant durations (#16728)
• Toggle coalesce in join if non-coalesced key isn't projected (#16677)
• Make dt.truncate 1.5x faster when every is just a single duration (and not an expression) (#16666)
• Always prune unused columns in semi/anti join (#16665)

✨ Enhancements

• Update DataFrame.pivot to allow index=None when values is set (#17126)
• Make hive_partitioning parameter default to None, which is automatically enabled for single directory inputs, and disabled otherwise (#17106)
• Improve ipython autocomplete for LazyFrame and DataFrame (#17091)
• Split replace functionality into two separate functions (#16921)
• Improve schema inference for hive partitions (#17079)
• Rename DataFrame.melt to unpivot and make parameters consistent with pivot (#17095)
• print row index in explain + dot (#17074)
• Support top-level pl.col autocompletion for iPython (#17080)
• Remove re-export of exceptions at top-level (#17059)
• predicate + projection pushdown in NDJson (#17068)
• Allow (non-)coalescing in join_asof (#17066)
• Turn of coalescing and fix mutation of join on expressions (#17061)
• Expand NDJson glob into one SCAN (#17063)
• Do not parse hive partitions from user provided directory/glob path (#17055)
• Support directory paths in scans for Parquet, IPC and CSV (#17017)
• Implement general array equality checks (#17043)
• Add strict parameter to DataFrame/LazyFrame.drop and fix behavior to default to True (#17044)
• Rename ModuleUpgradeRequired and PolarsPanicError error, remove InvalidAssert error (#17033)
• Add rechunk parameter to read_delta (#16991)
• allow experimental metadata use on release (#17005)
• first working prototype of new streaming engine (#16970)
• Add simple version of json_normalize (#17015)
• Change data orientation inference logic for DataFrame construction and warn when row orientation is inferred (#16976)
• Desugar AND filter into multiple nodes (#16992)
• Handle textio even if not correct (#16971)
• Properly apply strict parameter in Series constructor (#16939)
• Add SQL support for INTERSECT and EXCEPT ops (#16960)
• Add PerformanceWarning to LazyFrame properties (#16964)
• Add collect_schema method to LazyFrame and DataFrame (#16929)
• Allow setting file cache TTL on a per-file basis (#16891)
• Support Decimal inputs for lit (#16950)
• Implement multiply and division for lhs duration (#16948)
• Raise on invalid temporal arithmetic (#16934)
• Always end with a in-memory sink on collect (#16928)
• add style namespace (which defers to Great Tables) (#16809)
• Add Schema class (#16873)
• Normalize value_counts (#16917)
• add eq/ne for more FixedSizeLists (#16902)
• setup skeleton (#16900)
• add fundamentals for new async-based streaming execution engine (#16884)
• Cache downloaded cloud IPC files (#16892)
• Consistently convert to given time zone in Series constructor (#16828)
• Improve read_csv SQL table reading function defaults (better handle dates) (#16866)
• Support SQL VALUES clause and inline renaming of columns in CTE & derived table definitions (#16851)
• Support Python Enum values in lit (#16858)
• convert to give time zone in .str.to_datetime when values are offset-aware (#16742)
• Update reshape to return Array types instead of List types (#16825)
• Default to raising on out-of-bounds indices in all get/gather operations (#16841)
• Support SQL "SELECT" with no tables, optimise registration of globals (#16836)
• Native selector XOR set operation, guarantee consistent selector column-order (#16833)
• Extend recognised EXTRACT and DATE_PART SQL part abbreviations (#16767)
• Improve error message when raising integers to negative integers, improve docs (#16827)
• Return datetime for mean/median of Date colum (#16795)
• Update set_sorted to only accept a single column (#16800)
• Expose overflowing cast (#16805)
• Update group_by iteration and partition_by to always return tuple keys (#16793)
• Support array arithmetic for equally sized shapes (#16791)
• Expedited removal of certain deprecated functionality (2) (#16779)
• Removal of read_database_uri passthrough from read_database (#16783)
• Remove pyxlsb engine from read_database (#16784)
• Add check_order parameter to assert_series_equal (#16778)
• Enforce deprecation of keyword arguments as positional (#16755)
• Support cloud storage in scan_csv (#16674)
• Streamline SQL INTERVAL handling and improve related error messages, update sqlparser-rs lib (#16744)
• Support use of ordinal values in SQL ORDER BY clause (#16745)
• Support executing polars SQL against pandas and pyarrow objects (#16746)
• Remove deprecated parameters in Series.cut/qcut and update struct field names (#16741)
• Expedited removal of certain deprecated functionality (#16754)
• Remove deprecated functionality from rolling methods (#16750)
• Update date_range to no longer produce datetime ranges (#16734)
• Mark min_periods as keyword-only for rolling methods (#16738)
• Remove deprecated top_k parameters nulls_last, maintain_order, and multithreaded (#16599)
• Support order-by in window functions (#16743)
• Add SQL support for NULLS FIRST/LAST ordering (#16711)
• Update some error types to more appropriate variants (#15030)
• Initial SQL support for INTERVAL strings (#16732)
• Scheduled removal of deprecated functionality (2) (#16724)
• Scheduled removal of deprecated functionality (#16715)
• Enforce deprecation of offset arg in truncate and round (#16655)
• Change default offset in group_by_dynamic from 'negative every' to 'zero' (#16658)
• Constrain access to globals from DataFrame.sql in favor of top-level pl.sql (#16598)
• Read 2D NumPy arrays as Array type instead of List (#16710)
• Upda...

Rust Polars 0.41.0

💥 Breaking changes

• Make hive_partitioning parameter default to None, which is automatically enabled for single directory inputs, and disabled otherwise (#17106)
• Split replace functionality into two separate functions (#16921)
• Rename DataFrame.melt to unpivot and make parameters consistent with pivot (#17095)
• Default to writing binview data to IPC (#17084)
• Do not parse hive partitions from user provided directory/glob path (#17055)
• Add strict parameter to DataFrame/LazyFrame.drop and fix behavior to default to True (#17044)
• Remove supertype definition of List and non-List types (#16918)
• Native selector XOR set operation, guarantee consistent selector column-order (#16833)
• move offset_by implementation from polars-plan to polars-time, rename feature from DateOffset to OffsetBy (#16796)
• Rename str.concat to str.join and update default delimiter (#16790)
• Remove deprecated parameters in Series.cut/qcut and update struct field names (#16741)
• Expedited removal of certain deprecated functionality (#16754)
• Update some error types to more appropriate variants (#15030)
• Change default offset in group_by_dynamic from 'negative every' to 'zero' (#16658)
• Update clip to no longer propagate nulls in the given bounds (#14413)
• Change str.to_datetime to default to microsecond precision for format specifiers "%f" and "%.f" (#13597)
• Update resulting column names in pivot when pivoting by multiple values (#16439)
• Preserve nulls in ewm_mean, ewm_std, and ewm_var (#15503)
• Restrict casting for temporal data types (#14142)
• Rename struct fields of rle output to len/value and update data type of len field (#15249)
• Add check_names parameter to Series.equals and default to False (#16610)
• Deprecate str.explode in favor of str.split("").explode() (#16508)
• Deprecate how="outer" join type in favour of how="full" (left/right are *also* outer joins) (#16417)
• Change DataFrame.is_empty() to check height == 0 instead of width == 0 (#16351)

🚀 Performance improvements

• Default to writing binview data to IPC (#17084)
• Parallelize arrow conversion if binview -> large_bin (#17083)
• GC buffers in if_then_else view kernel (#16993)
• Desugar AND filter into multiple nodes (#16992)
• Optimize generic argsort of row-encoding (#16894)
• Improve rle_id iteration perf and set sorted flags (#16893)
• Optimize string/binary sort (#16871)
• Use split_at in split (#16865)
• Use split_at instead of double slice in chunk splits. (#16856)
• Don't rechunk in align_ if arrays are aligned (#16850)
• Don't create small chunks in parallel collect. (#16845)
• Add dedicated no-null branch in arg_sort (#16808)
• Speed up dt.offset_by 2x for constant durations (#16728)
• Toggle coalesce in join if non-coalesced key isn't projected (#16677)
• Make dt.truncate 1.5x faster when every is just a single duration (and not an expression) (#16666)
• Always prune unused columns in semi/anti join (#16665)
• make truncate 4x faster in simple cases (#16615)
• Cache arena's (and conversion) in SQL context (#16566)
• Partial schema cache. (#16549)
• improved numeric fill_(forward/backward) (#16475)
• only rechunk once per aggregate (#16469)
• Fix pathological small chunk parquet writing (#16433)

✨ Enhancements

• Make hive_partitioning parameter default to None, which is automatically enabled for single directory inputs, and disabled otherwise (#17106)
• Split replace functionality into two separate functions (#16921)
• Improve schema inference for hive partitions (#17079)
• Rename DataFrame.melt to unpivot and make parameters consistent with pivot (#17095)
• print row index in explain + dot (#17074)
• Support top-level pl.col autocompletion for iPython (#17080)
• predicate + projection pushdown in NDJson (#17068)
• Allow (non-)coalescing in join_asof (#17066)
• Turn of coalescing and fix mutation of join on expressions (#17061)
• Expand NDJson glob into one SCAN (#17063)
• Do not parse hive partitions from user provided directory/glob path (#17055)
• Support directory paths in scans for Parquet, IPC and CSV (#17017)
• Implement general array equality checks (#17043)
• Add strict parameter to DataFrame/LazyFrame.drop and fix behavior to default to True (#17044)
• allow experimental metadata use on release (#17005)
• first working prototype of new streaming engine (#16970)
• Desugar AND filter into multiple nodes (#16992)
• use min/max metadata on debug builds with POLARS_METADATA_FLAGS=extensive (#16963)
• Add SQL support for INTERSECT and EXCEPT ops (#16960)
• Allow setting file cache TTL on a per-file basis (#16891)
• Implement multiply and division for lhs duration (#16948)
• Raise on invalid temporal arithmetic (#16934)
• Always end with a in-memory sink on collect (#16928)
• Normalize value_counts (#16917)
• add eq/ne for more FixedSizeLists (#16902)
• setup skeleton (#16900)
• add fundamentals for new async-based streaming execution engine (#16884)
• Cache downloaded cloud IPC files (#16892)
• Improve read_csv SQL table reading function defaults (better handle dates) (#16866)
• Support SQL VALUES clause and inline renaming of columns in CTE & derived table definitions (#16851)
• convert to give time zone in .str.to_datetime when values are offset-aware (#16742)
• Support SQL "SELECT" with no tables, optimise registration of globals (#16836)
• Native selector XOR set operation, guarantee consistent selector column-order (#16833)
• Extend recognised EXTRACT and DATE_PART SQL part abbreviations (#16767)
• Improve error message when raising integers to negative integers, improve docs (#16827)
• Return datetime for mean/median of Date colum (#16795)
• Expose overflowing cast (#16805)
• Expose a few more expression nodes in the expression IR (#16781)
• Support array arithmetic for equally sized shapes (#16791)
• Support cloud storage in scan_csv (#16674)
• Streamline SQL INTERVAL handling and improve related error messages, update sqlparser-rs lib (#16744)
• Support use of ordinal values in SQL ORDER BY clause (#16745)
• Support executing polars SQL against pandas and pyarrow objects (#16746)
• add env locked metadata functions (#16719)
• Remove deprecated parameters in Series.cut/qcut and update struct field names (#16741)
• Expedited removal of certain deprecated functionality (#16754)
• Update date_range to no longer produce datetime ranges (#16734)
• Remove deprecated top_k parameters nulls_last, maintain_order, and multithreaded (#16599)
• Support order-by in window functions (#16743)
• Add SQL support for NULLS FIRST/LAST ordering (#16711)
• Update some error types to more appropriate variants (#15030)
• Initial SQL support for INTERVAL strings (#16732)
• Enforce deprecation of offset arg in truncate and round (#16655)
• eliminate ProjectionExprs and handle CSE by stacking extra columns (#16682)
• Change default offset in group_by_dynamic from 'negative every' to 'zero' (#16658)
• Update clip to no longer propagate nulls in the given bounds (#14413)
• Change str.to_datetime to default to microsecond precision for format specifiers "%f" and "%.f" (#13597)
• Update resulting column names in pivot when pivoting by multiple values (#16439)
• Preserve nulls in ewm_mean, ewm_std, and ewm_var (#15503)
• Restrict casting for temporal data types (#14142)
• Add many more auto-inferable datetime formats for str.to_datetime (#16634)
• Rename struct fields of rle output to len/value and update data type of len field (#15249)
• Add check_names parameter to Series.equals and default to False (#16610)
• Dedicated SQLInterface and SQLSyntax errors (#16635)
• Add DIV function support to the SQL interface (#16678)
• add additional control to write_parquet::statistics parameter (#16575)
• Support non-coalescing streaming left join (#16672)
• Allow wildcard and exclude before struct expansions (#16671)
• Support per-column nulls_last on sort operations (#16639)
• Add split_at method to arrow Array (#16620)
• Initial support for SQL ARRAY literals and the UNNEST table function (#16330)
• Don't allow struct.with_fields in grouping (#16629)
• Add SQL support for TRY_CAST function (#16589)
• add fuzzer for expressions (#16581)
• handle CSE dtypes in NodeTraverser.get_dtype (#16552)
• check if by column is sorted, rather than just checking sorted flag, in group_by_dynamic, upsample, and rolling (#16494)
• Add general metadata structure to ChunkedArray (#16399)
• Add is_column_selection() to expression meta, enhance expand_selector (#16479)
• NDarray/Tensor support (#16466)
• Allow designation of a custom name for the value_counts "count" column (#16434)
• Default rechunk=False for read_parquet (#16427)
• Add field expression as selector with an struct scope (#16402)
• Field expansion renaming (#16397)
• add cluster_with_columns plan optimization (#16274)
• Change DataFrame.is_empty() to check height == 0 instead of width == 0 (#16351)
• add Expr.interpolate_by (#16313)

🐞 Bug fixes

• Expand i128 primitive type match (#17076)
• Fix decompress_impl for csv with n_rows set (#17118)
• adds "polars-ops/timezones" dependency for "timezones" feature (#17115)
• Fix incorrect window std for chunked series (#17110)
• make GetOutput::get_field fallible (#17114)
• bubble error when no available bitrepr (#17116)
• Fix melt panic (#17088)
• Exclude index from expansion in rolling/group_by_dynamic (#17086)
• fix #17043 binary compare (#17052)
• Fix oob of join with literals and empty table (#17047)
• Don't silently accept multi-table FROM clauses (implicit JOIN syntax) (#17028)
• fix get categories on multiple row groups (#17041...

Python Polars 1.0.0-beta.1

💥 Breaking changes

• Change data orientation inference logic for DataFrame construction and warn when row orientation is inferred (#16976)
• Properly apply strict parameter in Series constructor (#16939)
• Remove supertype definition of List and non-List types (#16918)
• Consistently convert to given time zone in Series constructor (#16828)
• Update reshape to return Array types instead of List types (#16825)
• Default to raising on out-of-bounds indices in all get/gather operations (#16841)
• Native selector XOR set operation, guarantee consistent selector column-order (#16833)
• Set infer_schema_length as keyword-only argument in str.json_decode (#16835)
• Update set_sorted to only accept a single column (#16800)
• Remove deprecated parameters in Series.cut/qcut and update struct field names (#16741)
• Expedited removal of certain deprecated functionality (#16754)
• Update some error types to more appropriate variants (#15030)
• Scheduled removal of deprecated functionality (#16715)
• Change default offset in group_by_dynamic from 'negative every' to 'zero' (#16658)
• Constrain access to globals from DataFrame.sql in favor of top-level pl.sql (#16598)
• Read 2D NumPy arrays as Array type instead of List (#16710)
• Update clip to no longer propagate nulls in the given bounds (#14413)
• Change str.to_datetime to default to microsecond precision for format specifiers "%f" and "%.f" (#13597)
• Update resulting column names in pivot when pivoting by multiple values (#16439)
• Preserve nulls in ewm_mean, ewm_std, and ewm_var (#15503)
• Restrict casting for temporal data types (#14142)
• Support Decimal types by default when converting from Arrow (#15324)
• Remove serde functionality from pl.read_json and DataFrame.write_json (#16550)
• Update function signature of nth to allow positional input of indices, remove columns parameter (#16510)
• Rename struct fields of rle output to len/value and update data type of len field (#15249)
• Remove class variables from some DataTypes (#16524)
• Add check_names parameter to Series.equals and default to False (#16610)

⚠️ Deprecations

• Deprecate dt.mean/dt.median in favor of mean/median (#16888)
• Deprecate LazyFrame.with_context in favor of horizontal concatenation (#16860)
• Rename parameter descending to reverse in top_k methods (#16817)
• Rename str.concat to str.join and update default delimiter (#16790)
• Deprecate arctan2d in favor of arctan2(...).degrees() (#16786)

🚀 Performance improvements

• GC buffers in if_then_else view kernel (#16993)
• Desugar AND filter into multiple nodes (#16992)
• Optimize generic argsort of row-encoding (#16894)
• Improve rle_id iteration perf and set sorted flags (#16893)
• Optimize string/binary sort (#16871)
• Use split_at in split (#16865)
• Use split_at instead of double slice in chunk splits. (#16856)
• Don't rechunk in align_ if arrays are aligned (#16850)
• Don't create small chunks in parallel collect. (#16845)
• Add dedicated no-null branch in arg_sort (#16808)
• Speed up dt.offset_by 2x for constant durations (#16728)
• Toggle coalesce in join if non-coalesced key isn't projected (#16677)
• Make dt.truncate 1.5x faster when every is just a single duration (and not an expression) (#16666)
• Always prune unused columns in semi/anti join (#16665)

✨ Enhancements

• allow experimental metadata use on release (#17005)
• first working prototype of new streaming engine (#16970)
• Add simple version of json_normalize (#17015)
• Change data orientation inference logic for DataFrame construction and warn when row orientation is inferred (#16976)
• Desugar AND filter into multiple nodes (#16992)
• Handle textio even if not correct (#16971)
• Properly apply strict parameter in Series constructor (#16939)
• Add SQL support for INTERSECT and EXCEPT ops (#16960)
• Add PerformanceWarning to LazyFrame properties (#16964)
• Add collect_schema method to LazyFrame and DataFrame (#16929)
• Allow setting file cache TTL on a per-file basis (#16891)
• Support Decimal inputs for lit (#16950)
• Implement multiply and division for lhs duration (#16948)
• Raise on invalid temporal arithmetic (#16934)
• Always end with a in-memory sink on collect (#16928)
• add style namespace (which defers to Great Tables) (#16809)
• Add Schema class (#16873)
• Normalize value_counts (#16917)
• add eq/ne for more FixedSizeLists (#16902)
• setup skeleton (#16900)
• add fundamentals for new async-based streaming execution engine (#16884)
• Cache downloaded cloud IPC files (#16892)
• Consistently convert to given time zone in Series constructor (#16828)
• Improve read_csv SQL table reading function defaults (better handle dates) (#16866)
• Support SQL VALUES clause and inline renaming of columns in CTE & derived table definitions (#16851)
• Support Python Enum values in lit (#16858)
• convert to give time zone in .str.to_datetime when values are offset-aware (#16742)
• Update reshape to return Array types instead of List types (#16825)
• Default to raising on out-of-bounds indices in all get/gather operations (#16841)
• Support SQL "SELECT" with no tables, optimise registration of globals (#16836)
• Native selector XOR set operation, guarantee consistent selector column-order (#16833)
• Extend recognised EXTRACT and DATE_PART SQL part abbreviations (#16767)
• Improve error message when raising integers to negative integers, improve docs (#16827)
• Return datetime for mean/median of Date colum (#16795)
• Update set_sorted to only accept a single column (#16800)
• Expose overflowing cast (#16805)
• Update group_by iteration and partition_by to always return tuple keys (#16793)
• Support array arithmetic for equally sized shapes (#16791)
• Expedited removal of certain deprecated functionality (2) (#16779)
• Removal of read_database_uri passthrough from read_database (#16783)
• Remove pyxlsb engine from read_database (#16784)
• Add check_order parameter to assert_series_equal (#16778)
• Enforce deprecation of keyword arguments as positional (#16755)
• Support cloud storage in scan_csv (#16674)
• Streamline SQL INTERVAL handling and improve related error messages, update sqlparser-rs lib (#16744)
• Support use of ordinal values in SQL ORDER BY clause (#16745)
• Support executing polars SQL against pandas and pyarrow objects (#16746)
• Remove deprecated parameters in Series.cut/qcut and update struct field names (#16741)
• Expedited removal of certain deprecated functionality (#16754)
• Remove deprecated functionality from rolling methods (#16750)
• Update date_range to no longer produce datetime ranges (#16734)
• Mark min_periods as keyword-only for rolling methods (#16738)
• Remove deprecated top_k parameters nulls_last, maintain_order, and multithreaded (#16599)
• Support order-by in window functions (#16743)
• Add SQL support for NULLS FIRST/LAST ordering (#16711)
• Update some error types to more appropriate variants (#15030)
• Initial SQL support for INTERVAL strings (#16732)
• Scheduled removal of deprecated functionality (2) (#16724)
• Scheduled removal of deprecated functionality (#16715)
• Enforce deprecation of offset arg in truncate and round (#16655)
• Change default offset in group_by_dynamic from 'negative every' to 'zero' (#16658)
• Constrain access to globals from DataFrame.sql in favor of top-level pl.sql (#16598)
• Read 2D NumPy arrays as Array type instead of List (#16710)
• Update clip to no longer propagate nulls in the given bounds (#14413)
• Change str.to_datetime to default to microsecond precision for format specifiers "%f" and "%.f" (#13597)
• Update resulting column names in pivot when pivoting by multiple values (#16439)
• Preserve nulls in ewm_mean, ewm_std, and ewm_var (#15503)
• Restrict casting for temporal data types (#14142)
• Add many more auto-inferable datetime formats for str.to_datetime (#16634)
• Support Decimal types by default when converting from Arrow (#15324)
• Remove serde functionality from pl.read_json and DataFrame.write_json (#16550)
• Update function signature of nth to allow positional input of indices, remove columns parameter (#16510)
• Rename struct fields of rle output to len/value and update data type of len field (#15249)
• Remove class variables from some DataTypes (#16524)
• Add check_names parameter to Series.equals and default to False (#16610)
• Dedicated SQLInterface and SQLSyntax errors (#16635)
• Add DIV function support to the SQL interface (#16678)
• Support non-coalescing streaming left join (#16672)
• Allow wildcard and exclude before struct expansions (#16671)

🐞 Bug fixes

• properly catch not found explode cols (#17020)
• Correctly convert data frames to NumPy for C index order (#17000)
• Raise on invalid arithmetic shapes (#16986)
• Don't pushdown predicates in cross join if the refer to both tables (#16983)
• Fix projection pushdown with literal joins (#16981)
• Fix edge case in DataFrame constructor data orientation inference (#16975)
• Raise on list of objects (#16959)
• Handle strictness for Decimal Series construction (#15309)
• Don't panic in object to anyvalue (#16957)
• properly set FAST_EXPLODE_LIST metadata (#16951)
• Raise informative error when writing object to file (#16954)
• Remove supertype definition of List and non-List types (#16918)
• Remove unwrap in extend() (#16890)
• Fix should_rechunk check (#16852)
• Ensure read_excel and read_ods return identical frames across all engines when given empty spreadsheet tables (#16802)
• Consistent behaviour when "infer_schema_length=0" for read_excel (#16840)
• Standardised additional SQL interface errors (#16829)
• Ensure that splitted ChunkedArray also flattens chunks (#16837)
• Reduce needless panics in comparisons (#16831)
  -...

Python Polars 1.0.0-alpha.1

💥 Breaking changes

• Consistently convert to given time zone in Series constructor (#16828)
• Update reshape to return Array types instead of List types (#16825)
• Default to raising on out-of-bounds indices in all get/gather operations (#16841)
• Native selector XOR set operation, guarantee consistent selector column-order (#16833)
• Set infer_schema_length as keyword-only argument in str.json_decode (#16835)
• Update set_sorted to only accept a single column (#16800)
• Update group_by iteration and partition_by to always return tuple keys (#16793)
• Default to coalesce=False in left outer join (#16769)
• Remove pyxlsb engine from read_database (#16784)
• Remove deprecated parameters in Series.cut/qcut and update struct field names (#16741)
• Expedited removal of certain deprecated functionality (#16754)
• Remove deprecated top_k parameters nulls_last, maintain_order, and multithreaded (#16599)
• Update some error types to more appropriate variants (#15030)
• Scheduled removal of deprecated functionality (#16715)
• Enforce deprecation of offset arg in truncate and round (#16655)
• Change default offset in group_by_dynamic from 'negative every' to 'zero' (#16658)
• Constrain access to globals from DataFrame.sql in favor of top-level pl.sql (#16598)
• Read 2D NumPy arrays as multidimensional Array instead of List (#16710)
• Update clip to no longer propagate nulls in the given bounds (#14413)
• Change str.to_datetime to default to microsecond precision for format specifiers "%f" and "%.f" (#13597)
• Update resulting column names in pivot when pivoting by multiple values (#16439)
• Preserve nulls in ewm_mean, ewm_std, and ewm_var (#15503)
• Restrict casting for temporal data types (#14142)
• Support Decimal types by default when converting from Arrow (#15324)
• Remove serde functionality from pl.read_json and DataFrame.write_json (#16550)
• Update function signature of nth to allow positional input of indices, remove columns parameter (#16510)
• Rename struct fields of rle output to len/value and update data type of len field (#15249)
• Remove class variables from some DataTypes (#16524)
• Add check_names parameter to Series.equals and default to False (#16610)

⚠️ Deprecations

• Deprecate LazyFrame.with_context (#16860)
• Rename parameter descending to reverse in top_k methods (#16817)
• Rename str.concat to str.join (#16790)
• Deprecate arctan2d (#16786)

🚀 Performance improvements

• Optimize string/binary sort (#16871)
• Use split_at in split (#16865)
• Use split_at instead of double slice in chunk splits. (#16856)
• Don't rechunk in align_ if arrays are aligned (#16850)
• Don't create small chunks in parallel collect. (#16845)
• Add dedicated no-null branch in arg_sort (#16808)
• Speed up dt.offset_by 2x for constant durations (#16728)
• Toggle coalesce if non-coalesced key isn't projected (#16677)
• Make dt.truncate 1.5x faster when every is just a single duration (and not an expression) (#16666)
• Always prune unused columns in semi/anti join (#16665)

✨ Enhancements

• Consistently convert to given time zone in Series constructor (#16828)
• Improve read_csv SQL table reading function defaults (better handle dates) (#16866)
• Support SQL VALUES clause and inline renaming of columns in CTE & derived table definitions (#16851)
• Support Python Enum values in lit (#16858)
• convert to give time zone in .str.to_datetime when values are offset-aware (#16742)
• Update reshape to return Array types instead of List types (#16825)
• Default to raising for oob on all get/gather operations (#16841)
• Support SQL "SELECT" with no tables, optimise registration of globals (#16836)
• Native selector XOR set operation, guarantee consistent selector column-order (#16833)
• Extend recognised EXTRACT and DATE_PART SQL part abbreviations (#16767)
• Improve error message when raising integers to negative integers, improve docs (#16827)
• Return datetime for mean/median of Date colum (#16795)
• Only accept a single column in set_sorted (#16800)
• Expose overflowing cast (#16805)
• Update group-by iteration to always return tuple keys (#16793)
• Support array arithmetic for equally sized shapes (#16791)
• Default to coalesce=False in left outer join (#16769)
• More removal of deprecated functionality (#16779)
• Removal of read_database_uri passthrough from read_database (#16783)
• Remove pyxlsb engine from read_database (#16784)
• Add check_order parameter to assert_series_equal (#16778)
• Enforce deprecation of keyword arguments as positional (#16755)
• Support cloud storage in scan_csv (#16674)
• Streamline SQL INTERVAL handling and improve related error messages, update sqlparser-rs lib (#16744)
• Support use of ordinal values in SQL ORDER BY clause (#16745)
• Support executing polars SQL against pandas and pyarrow objects (#16746)
• Remove deprecated parameters in Series.cut/qcut (#16741)
• Expedited removal of certain deprecated functionality (#16754)
• Remove deprecated functionality from rolling methods (#16750)
• Update date_range to no longer produce datetime ranges (#16734)
• Mark min_periods as keyword-only for rolling methods (#16738)
• Remove deprecated top_k parameters (#16599)
• Support order-by in window functions (#16743)
• Add SQL support for NULLS FIRST/LAST ordering (#16711)
• Update some error types to more appropriate variants (#15030)
• Initial SQL support for INTERVAL strings (#16732)
• More scheduled removal of deprecated functionality (#16724)
• Scheduled removal of deprecated functionality (#16715)
• Enforce deprecation of offset arg in truncate and round (#16655)
• Change default of offset in group_by_dynamic from "negative every" to "zero" (#16658)
• Constrain access to globals from df.sql in favour of top-level pl.sql (#16598)
• Read 2D numpy arrays as Array[dt, shape] instead of Listst[dt] (#16710)
• Activate decimal by default (#16709)
• Do not propagate nulls in clip bounds (#14413)
• Change .str.to_datetime to default to microsecond precision for format specifiers "%f" and "%.f" (#13597)
• Remove redundant column name when pivoting by multiple values (#16439)
• Preserve nulls in ewm_mean, ewm_std, and ewm_var (#15503)
• Restrict casting for temporal data types (#14142)
• Add many more auto-inferable datetime formats for str.to_datetime (#16634)
• Support decimals by default when converting from Arrow (#15324)
• Remove serde functionality from pl.read_json and DataFrame.write_json (#16550)
• Update function signature of nth to allow positional input of indices, remove columns parameter (#16510)
• Rename struct fields of rle output to len/value and update data type of len field (#15249)
• Remove default class variable values on DataTypes (#16524)
• Add check_names parameter to Series.equals and default to False (#16610)
• Dedicated SQLInterface and SQLSyntax errors (#16635)
• Add DIV function support to the SQL interface (#16678)
• Support non-coalescing streaming left join (#16672)
• Allow wildcard and exclude before struct expansions (#16671)

🐞 Bug fixes

• Fix should_rechunk check (#16852)
• Ensure read_excel and read_ods return identical frames across all engines when given empty spreadsheet tables (#16802)
• Consistent behaviour when "infer_schema_length=0" for read_excel (#16840)
• Standardised additional SQL interface errors (#16829)
• Ensure that splitted ChunkedArray also flattens chunks (#16837)
• Reduce needless panics in comparisons (#16831)
• Reset if next caller clones inner series (#16812)
• Raise on non-positive json schema inference (#16770)
• Rewrite implementation of top_k/bottom_k and fix a variety of bugs (#16804)
• Fix comparison of UInt64 with zero (#16799)
• Fix incorrect parquet statistics written for UInt64 values > Int64::MAX (#16766)
• Fix boolean distinct (#16765)
• DATE_PART SQL syntax/parsing, improve some error messages (#16761)
• Include pl. qualifier for inner dtypes in to_init_repr (#16235)
• Column selection wasn't applied when reading CSV with no rows (#16739)
• Panic on empty df / null List(Categorical) (#16730)
• Only flush if operator can flush in streaming outer join (#16723)
• Raise unsupported cat array (#16717)
• Assert SQLInterfaceError is raised (#16713)
• Restrict casting for temporal data types (#14142)
• Handle nested categoricals in assert_series_equal when categorical_as_str=True (#16700)
• Improve read_database check for SQLAlchemy async Session objects (#16680)
• Reduce scope of multi-threaded numpy conversion (#16686)
• Full null on dyn int (#16679)
• Fix filter shape on empty null (#16670)

📖 Documentation

• Update version switcher for 1.0.0 prereleases (#16847)
• Update link from Python API reference to user guide (#16849)
• Update docstring/test/etc usage of select and with_columns to idiomatic form (#16801)
• Update versioning docs for 1.0.0 (#16757)
• Add docstring example for DataFrame.limit (#16753)
• Fix incorrect stated value of include_nulls in DataFrame.update docstring (#16701)
• Update deprecation docs in the user guide (#14315)
• Add example for index count in DataFrame.rolling (#16600)
• Improve docstring of Expr/Series.map_elements (#16079)
• Add missing polars.sql docs entry and small docstring update (#16656)

🛠️ Other improvements

• Remove inner Arc from FileCacheEntry (#16870)
• Do not update stable API reference on prerelease (#16846)
• Update links to API references (#16843)
• Prepare update of API reference URLs (#16816)
• Rename allow_overflow to wrap_numerical (#16807)
• Set infer_schema_length as keyword-only for str.json_decode (#168...

Python Polars 0.20.31

Important

The decision to change the default coalesce behavior of left join has been reversed.
You can ignore the associated deprecation warning.

⚠️ Deprecations

• Rename dtypes parameter to schema_overrides for read_csv/scan_csv/read_csv_batched (#16628)
• Deprecate nulls_last/maintain_order/multithreaded parameters for top_k methods (#16597)
• Rename SQLContext "eager_execution" param to "eager" (#16595)
• Rename Series.equals parameter strict to check_dtypes and rename assertion utils parameter check_dtype to check_dtypes (#16573)
• Add DataFrame.serialize/deserialize (#16545)
• Deprecate str.explode in favor of str.split("").explode() (#16508)
• Deprecate default coalesce behavior of left join (#16532) - !! Reversed in 1.0.0 - see message above !!

🚀 Performance improvements

• make truncate 4x faster in simple cases (#16615)
• Cache arena's (and conversion) in SQL context (#16566)
• Partial schema cache. (#16549)

✨ Enhancements

• Support per-column nulls_last on sort operations (#16639)
• Initial support for SQL ARRAY literals and the UNNEST table function (#16330)
• Don't allow struct.with_fields in grouping (#16629)
• improve support for user-defined functions that return scalars (#16556)
• Add SQL support for TRY_CAST function (#16589)
• Add top-level pl.sql function (#16528)
• Expose temporal function expression ops to expr ir (#16546)
• Add DataFrame.serialize/deserialize (#16545)
• check if by column is sorted, rather than just checking sorted flag, in group_by_dynamic, upsample, and rolling (#16494)

🐞 Bug fixes

• Potentially deal with empty range (#16650)
• Use of SQL ORDER BY should not cause reordering of SELECT cols (#16579)
• ensure df in empty parquet (#16621)
• Fix Array constructor when inner type is another Array (#16622)
• Fix parsing of shape in Array constructor and deprecate width parameter (#16567)
• Crash using empty Series in LazyFrame.select() (#16592)
• improve support for user-defined functions that return scalars (#16556)
• Resolve multiple SQL JOIN issues (#16507)
• Project last column if count query (#16569)
• Properly split struct columns (#16563)
• Ensure strict chunking in chunked partitioned group by (#16561)
• Error selecting columns after non-coalesced join (multiple join keys) (#16559)
• Don't panic on hashing nested list types (#16555)
• Crash selecting columns after non-coalesced join (#16541)
• Fix group gather of single literal (#16539)
• throw an invalid operation exception on performing a sum over a list of strs (#16521)
• Fix DataFrame.__getitem__ for empty list input - df[[]] (#16520)
• Fix issue in DataFrame.__getitem__ with 2 column inputs (#16517)

📖 Documentation

• Overview of available SQL functions (#16268)
• Update filter description to clarify that null evaluations are removed (#16632)
• Include warning in docstrings that accessing LazyFrame properties may be expensive (#16618)
• Add a few versionadded tags, and add is_column_selection to the Expr meta docs (#16590)
• Fix bullet points not rendering correctly in DataFrame.join docstring (#16576)
• Remove erroneous implode reference from the user guide section on window functions (#16544)

📦 Build system

• Run cargo update (#16574)

🛠️ Other improvements

• Add test for 16642 (#16646)
• Remove duplicate tag in CODEOWNERS (#16625)
• Update dprint hook versions and enable JSON linting (#16611)
• Fewer typing.no_type_check (#16497)

Thank you to all our contributors for making this release possible!
@MarcoGorelli, @alexander-beedie, @coastalwhite, @hattajr, @itamarst, @mcrumiller, @nameexhaustion, @r-brink, @ritchie46, @stinodego, @twoertwein and @wence-

Python Polars 0.20.30

⚠️ Deprecations

• Add Series/Expr.has_nulls and deprecate Series.has_validity (#16488)
• Deprecate tree_format parameter for LazyFrame.explain in favor of format (#16486)

🚀 Performance improvements

• improved numeric fill_(forward/backward) (#16475)
• only rechunk once per aggregate (#16469)

✨ Enhancements

• Minor DataFrame.__getitem__ improvements (#16495)
• Add is_column_selection() to expression meta, enhance expand_selector (#16479)
• Add Series/Expr.has_nulls and deprecate Series.has_validity (#16488)
• NDarray/Tensor support (#16466)

🐞 Bug fixes

• Fix df.chunked for struct (#16504)
• Mix of column and field expansion (#16502)
• Fix split_chunks for nested dtypes (#16493)
• Fix handling NaT values when creating Series from NumPy ndarray (#16490)
• Fix boolean trap issue in top_k/bottom_k (#16489)
• Handle struct.fields as special case of alias (#16484)
• Correct schema for list.sum (#16483)
• allow search_sorted directly on multiple chunks, and fix behavior around nulls (#16447)
• Fix use of COUNT(*) in SQL GROUP BY operations (#16465)
• respect nan_to_null when using multi-thread in pl.from_pandas (#16459)
• write_delta() apparently does support Categorical columns (#16454)

📖 Documentation

• Update the Overview section of the contributing guide (#15674)
• Use pl.field inside with_fields examples. (#16451)
• Change ordering of values in example for cum_max (#16456)

🛠️ Other improvements

• Refactor Series/DataFrame.__getitem__ logic (#16482)

Thank you to all our contributors for making this release possible!
@BGR360, @alexander-beedie, @cmdlineluser, @coastalwhite, @itamarst, @marenwestermann, @mdavis-xyz, @messense, @orlp, @ritchie46 and @stinodego

Python Polars 0.20.29

⚠️ Deprecations

• Deprecate how="outer" join type in favour of how="full" (left/right are *also* outer joins) (#16417)

🚀 Performance improvements

• Fix pathological small chunk parquet writing (#16433)

✨ Enhancements

• Support zero-copy conversion for temporal types in DataFrame.to_numpy (#16429)
• Allow designation of a custom name for the value_counts "count" column (#16434)
• Default rechunk=False for read_parquet (#16427)
• Add "ignore_spaces" to alpha and alphanumeric selectors, add "ascii_only" to digit (#16362)
• Update __array__ method for Series and DataFrame to support copy parameter (#16401)

🐞 Bug fixes

• add cluster_with_columns optimization toggle in python (#16446)
• Fix struct 'with_fields' schema for update dtypes (#16428)
• Fix error reading lists of CSV files that contain comments (#16426)
• make read_parquet() respect rechunk flag when using pyarrow (#16418)
• Improve read_excel dtype inference of "calamine" int/float results that include NaN (#16400)
• Update apply call in str_duration_ util. (#16412)

📖 Documentation

• Add interpolate_by entry to rst files. (#16422)
• Fix sphinx headers: 'Example' → 'Examples' (#16407)

Thank you to all our contributors for making this release possible!
@KDruzhkin, @alexander-beedie, @ankane, @cmdlineluser, @coastalwhite, @itamarst, @nameexhaustion, @ritchie46 and @stinodego

Python Polars 0.20.28

⚠️ Deprecations

• Deprecate use_pyarrow parameter for to_numpy methods (#16391)

✨ Enhancements

• Add field expression as selector with an struct scope (#16402)
• Field expansion renaming (#16397)
• Respect index order in DataFrame.to_numpy also for non-numeric frames (#16390)
• add Expr.interpolate_by (#16313)
• Implement Struct support for Series.to_numpy (#16383)

🐞 Bug fixes

• Fix struct arithmetic schema (#16396)
• Handle non-Sequence iterables in filter (#16254)
• Fix don't panic on chunked to_numpy conversion (#16393)
• Don't check nulls before conversion (#16392)
• Add support for generalized ufunc with different size input and output (#16336)
• Improve cursor close behaviour with respect to Oracle "thick mode" connections (#16380)
• Fix DataFrame.to_numpy for Array/Struct types (#16386)
• Handle ambiguous/nonexistent datetimes in Series construction (#16342)
• Fix DataFrame.to_numpy for Struct columns when structured=True (#16358)
• Use strings to expose ClosedInterval in expr IR (#16369)

📖 Documentation

• Expand docstrings for to_numpy methods (#16394)
• Add a not about index access on struct.field (#16389)

Thank you to all our contributors for making this release possible!
@MarcoGorelli, @alexander-beedie, @coastalwhite, @dangotbanned, @itamarst, @ritchie46, @stinodego and @wence-

Rust Polars 0.40.0

💥 Breaking changes

• Remove incremental read based batched CSV reader (#16259)
• separate rolling_*_by from rolling_*(..., by=...) in Rust (#16102)
• Move CSV read options from CsvReader to CsvReadOptions (#16126)
• Rename all 'Chunk's to RecordBatch (#16063)
• prepare for join coalescing argument (#15418)
• Rename to CsvParserOptions to CsvReaderOptions, use in CsvReader (#15919)
• Add context trace to LazyFrame conversion errors (#15761)
• Move schema resolving of file scan to IR phase (#15739)
• Move schema resolving to IR phase. (#15714)
• Rename LogicalPlan and builders to reflect their uses better (#15712)

🚀 Performance improvements

• Use branchless uleb128 decoding for parquet (#16352)
• Reduce error bubbling in parquet hybrid_rle (#16348)
• use is_sorted in ewm_mean_by, deprecate check_sorted (#16335)
• Optimize is_sorted for numeric data (#16333)
• do not use pyo3-built (#16309)
• Faster bitpacking for Parquet writer (#16278)
• Avoid importing ctypes.util in CPU check script if possible (#16307)
• Don't rechunk when converting DataFrame to numpy/ndarray (#16288)
• use zeroed vec in ewm_mean_by for sorted fastpath (#16265)
• use zeroable_vec in ewm_mean_by (#16166)
• Improve cost of chunk_idx compute (#16154)
• Don't rechunk by default in concat (#16128)
• Ensure rechunk is parallel (#16127)
• Don't traverse deep datasets that we repr as union in CSE (#16096)
• Ensure better chunk sizes (#16071)
• Don't rechunk in parallel collection (#15907)
• Improve non-trivial list aggregations (#15888)
• Ensure we hit specialized gather for binary/strings (#15886)
• Limit the cache size for to_datetime (#15826)
• skip initial null items and don't recompute slope in interpolate (#15819)
• Fix quadratic in binview growable same source (#15734)

✨ Enhancements

• Raise when joining on the same keys twice (#16329)
• Don't require data to be sorted by by column in rolling_*_by operations (#16249)
• Add struct.field expansion (regex, wildcard, columns) (#16320)
• Faster bitpacking for Parquet writer (#16278)
• Add struct.with_fields (#16305)
• Handle implicit SQL string → temporal conversion in the BETWEEN clause (#16279)
• Add new index/range based selector cs.by_index, allow multiple indices for nth (#16217)
• Show warning if expressions are very deep (#16233)
• Native CSV file list reading (#16180)
• Register memory mapped files and raise when written to (#16208)
• Raise when encountering invalid supertype in functions during conversion (#16182)
• Add SQL support for GROUP BY ALL syntax and fix several issues with aliased group keys (#16179)
• Allow implicit string → temporal conversion in SQL comparisons (#15958)
• separate rolling_*_by from rolling_*(..., by=...) in Rust (#16102)
• Add run-length encoding to Parquet writer (#16125)
• add date pattern dd.mm.YYYY (#16045)
• Add RLE to RLE_DICTIONARY encoder (#15959)
• Support non-coalescing joins in default engine (#16036)
• Move diagonal & horizontal concat schema resolving to IR phase (#16034)
• raise more informative error messages in rolling_* aggregations instead of panicking (#15979)
• Convert concat during IR conversion (#16016)
• Improve dynamic supertypes (#16009)
• Additional uint datatype support for the SQL interface (#15993)
• Support Decimal read from IPC (#15965)
• Add typed collection from par iterators (#15961)
• Add by argument for Expr.top_k and Expr.bottom_k (#15468)
• Add option to disable globbing in csv (#15930)
• Add option to disable globbing in parquet (#15928)
• Rename to CsvParserOptions to CsvReaderOptions, use in CsvReader (#15919)
• Expressify dt.round (#15861)
• Improve error messages in context stack (#15881)
• Add dynamic literals to ensure schema correctness (#15832)
• dt.truncate supports broadcasting lhs (#15768)
• Expressify str.json_path_match (#15764)
• Support decimal float parsing in CSV (#15774)
• Add context trace to LazyFrame conversion errors (#15761)

🐞 Bug fixes

• correct AExpr.to_field for bitwise and logical and/or (#16360)
• cargo clippy for uleb128 safety comment (#16368)
• Infer CSV schema as supertype of all files (#16349)
• Address overflow combining u64 hashes in Debug builds (#16323)
• Don't exclude explicitly named columns in group-by context' expr expansion (#16318)
• Harden Series.reshape against invalid parameters (#16281)
• Fix list.sum dtype for boolean (#16290)
• Don't stackoverflow on all/any horizontal (#16287)
• compilation error when both lazy and ipc features are enabled (#16284)
• `rolling_*_by was throwing incorrect error when dataframe was sorted by contained multiple chunks (#16247)
• Clippy Error for CPUID (#16241)
• Reading CSV with low_memory gave no data (#16231)
• Empty unique (#16214)
• Fix empty drop nulls (#16213)
• Fix get expression group-by state (#16189)
• Fix rolling empty group OOB (#16186)
• offset=-0i was being treated differently to offset=0i in rolling (#16184)
• Fix panic on empty frame joins (#16181)
• Fix streaming glob slice (#16174)
• Fix CSV skip_rows_after_header for streaming (#16176)
• Flush parquet at end of batches tick (#16073)
• Check CSE name aliases for collisions. (#16149)
• Don't override CSV reader encoding with lossy UTF-8 (#16151)
• Add missing allow macros for windows (#16130)
• Ensure hex and bitstring literals work inside SQL IN clauses (#16101)
• Revert "Add RLE to RLE_DICTIONARY encoder" (#16113)
• Respect user passed 'reader_schema' in 'scan_csv' (#16080)
• Lazy csv + projection; respect null values arg (#16077)
• Materialize dtypes when converting to arrow (#16074)
• Fix casting decimal to decimal for high precision (#16049)
• Fix printing max scale decimals (#16048)
• Decimal supertype for dyn int (#16046)
• Do not set sorted flag on lexical sorting (#16032)
• properly handle nulls in DictionaryArray::iter_typed (#16013)
• Fix CSE case where upper plan has no projection (#16011)
• Crash/incorrect group_by/n_unique on categoricals created by (q)cut (#16006)
• Ternary supertype dynamics (#15995)
• Treat splitting by empty string as iterating over chars (#15922)
• Fix PartialEq for DataType::Unknown (#15992)
• Do not reverse null indices in descending arg_sort (#15974)
• Finish adding typed_lit to help schema determination in SQL "extract" func (#15955)
• do not panic when comparing against categorical with incompatible dtype (#15857)
• Join validation for multiple keys (#15947)
• Set default limit for String column display to 30 and fix edge cases (#15934)
• typo in add_half_life takes ln(negative) (#15932)
• Remove ffspec from parquet reader (#15927)
• avoid WRITE+EXEC for CPUID check (#15912)
• fix inconsistent decimal formatting (#15457)
• Preserve NULLs for is_not_nan (#15889)
• double projection check should only take the upstream projections into account (#15901)
• Ensure we don't create invalid frames when combining unit lit + … (#15903)
• Clear cached rename schema (#15902)
• Fix OOB in struct lit/agg aggregation (#15891)
• create (q)cut labels in fixed order (#15843)
• Tag shrink_dtype as non-streaming (#15828)
• drop-nulls edge case; remove drop-nulls special case (#15815)
• ewm_mean_by was skipping initial nulls when it was already sorted by "by" column (#15812)
• Consult cgroups to determine free memory (#15798)
• raise if index count like 2i is used when performing rolling, group_by_dynamic, upsample, or other temporal operatios (#15751)
• Don't deduplicate sort that has slice pushdown (#15784)
• Fix incorrect is_between pushdown to scan_pyarrow_dataset (#15769)
• Handle null index correctly for list take (#15737)
• Preserve lexical ordering on concat (#15753)
• Remove incorrect unsafe pointer cast for int -> enum (#15740)
• pass series name to apply for cut/qcut (#15715)
• count of null column shouldn't panic in agg context (#15710)

📖 Documentation

• Clarify arrow usage (#16152)
• Solve inconsistency between code and comment (#16135)
• add filter docstring examples to date and datetime (#15996)
• update the link to R API docs (#15973)
• Fix a typo in categorical section of the user guide (#15777)
• Fix incorrect column name in LazyFrame.sort doc example (#15658)

📦 Build system

• Update Rust nightly toolchain version (#16222)
• Don't import jemalloc (#15942)
• Use default allocator for lts-cpu (#15941)
• replace all macos-latest referrals with macos-13 (#15926)
• pin mimalloc and macos-13 (#15925)
• use jemalloc in lts-cpu (#15913)

🛠️ Other improvements

• simplify interpolate code, add test for rolling_*_by with nulls (#16334)
• Move expression expansion to conversion module (#16331)
• Add polars-expr README (#16316)
• Move physical expressions to new crate (#16306)
• Use cls (not self) in classmethods (#16303)
• conditionally print the CSEs (#16292)
• Rename ChunkedArray.chunk_id to chunk_lengths (#16273)
• Use Scalar instead of Series some aggregations (#16277)
• Use CsvReadOptions in LazyCsvReader (#16283)
• Do not hardcode bash path in Makefile (#16263)
• Add IR::Reduce (not yet implemented) (#16216)
• Remove incremental read based batched CSV reader (#16259)
• move all describe, describe_tree and dot-viz code to IR instead of DslPlan (#16237)
• move describe to IR instead of DSL (#16191)
• Use Duration.is_zero instead of comparing Duration.duration_ns to 0 (#16195)
• Remove unused code (#16175)
• Don't override CSV reader encoding with lossy UTF-8 (#16151)
• Move CSV read options from CsvReader to CsvReadOptions (#16126)
• Bump sccache action (#16088)
• Fix failures in test coverage workflow (#16083)
• Rename all 'Chunk's to RecordBatch (#16063)
• Use UnionArgs for DSL side (#16017)
• Add some comments (#16008)
• prepare for join coalescing argument (#15418)
• Pin c...

Python Polars 0.20.27

Warning

This release was yanked. Please use the 0.20.28 release instead.

⚠️ Deprecations

• Change parameter chunked to allow_chunks in parametric testing strategies (#16264)

🚀 Performance improvements

• Use branchless uleb128 decoding for parquet (#16352)
• Reduce error bubbling in parquet hybrid_rle (#16348)
• use is_sorted in ewm_mean_by, deprecate check_sorted (#16335)
• Optimize is_sorted for numeric data (#16333)
• do not use pyo3-built (#16309)
• Faster bitpacking for Parquet writer (#16278)
• Improve Series.to_numpy performance for chunked Series that would otherwise be zero-copy (#16301)
• Further optimise initial polars import (#16308)
• Avoid importing ctypes.util in CPU check script if possible (#16307)
• Don't rechunk when converting DataFrame to numpy/ndarray (#16288)
• use zeroed vec in ewm_mean_by for sorted fastpath (#16265)

✨ Enhancements

• expose BooleanFunction in expr IR (#16355)
• Allow read_excel to handle bytes/BytesIO directly when using the "calamine" (fastexcel) engine (#16344)
• Raise when joining on the same keys twice (#16329)
• Don't require data to be sorted by by column in rolling_*_by operations (#16249)
• Support List types in Series.to_numpy (#16315)
• Add to_jax methods to support Jax Array export from DataFrame and Series (#16294)
• Enable generating data with time zones in parametric testing (#16298)
• Add struct.field expansion (regex, wildcard, columns) (#16320)
• Add new alpha, alphanumeric and digit selectors (#16310)
• Faster bitpacking for Parquet writer (#16278)
• Add require_all parameter to the by_name column selector (#15028)
• Start updating BytecodeParser for Python 3.13 (#16304)
• Add struct.with_fields (#16305)
• Handle implicit SQL string → temporal conversion in the BETWEEN clause (#16279)
• Expose string expression nodes to python (#16221)
• Add new index/range based selector cs.by_index, allow multiple indices for nth (#16217)
• Show warning if expressions are very deep (#16233)
• Fix some issues in parametric testing with nested dtypes (#16211)

🐞 Bug fixes

• pick a consistent order for the sort options in PyIR (#16350)
• Infer CSV schema as supertype of all files (#16349)
• Fix issue in parametric testing where excluded_dtypes list would grow indefinitely (#16340)
• Address overflow combining u64 hashes in Debug builds (#16323)
• Don't exclude explicitly named columns in group-by context' expr expansion (#16318)
• Improve map_elements typing (#16257)
• Harden Series.reshape against invalid parameters (#16281)
• Fix list.sum dtype for boolean (#16290)
• Don't stackoverflow on all/any horizontal (#16287)
• Fix Series.to_numpy for Array types with nulls and nested Arrays (#16230)
• `rolling_*_by was throwing incorrect error when dataframe was sorted by contained multiple chunks (#16247)
• Don't allow passing missing data to generalized ufuncs (#16198)
• Address overly-permissive expand_selectors function, minor fixes (#16250)
• Add missing support for parsing instantiated Object dtypes Object() (#16260)
• Reading CSV with low_memory gave no data (#16231)
• Add missing read_database overload (#16229)
• Fix a rounding error in parametric test datetimes generation (#16228)
• Fix some issues in parametric testing with nested dtypes (#16211)

📖 Documentation

• Add missing word in join docstring (#16299)
• document that month_start/month_end preserve the current time (#16293)
• Add example for separator parameter in pivot (#15957)

📦 Build system

• Fix allocator features (#16365)
• Update Rust nightly toolchain version (#16222)

🛠️ Other improvements

• Move DataFrame.to_numpy implementation to Rust side (#16354)
• Organize PyO3 NumPy code into interop::numpy module (#16346)
• simplify interpolate code, add test for rolling_*_by with nulls (#16334)
• Very minor refactor of DataFrame.to_numpy code (#16325)
• InterchangeDataFrame.version should be a ClassVar (not a property) (#16312)
• Add polars-expr README (#16316)
• Raise import timing test threshold (#16302)
• Use cls (not self) in classmethods (#16303)
• Use Scalar instead of Series some aggregations (#16277)
• Do not hardcode bash path in Makefile (#16263)
• Add IR::Reduce (not yet implemented) (#16216)
• move all describe, describe_tree and dot-viz code to IR instead of DslPlan (#16237)

Thank you to all our contributors for making this release possible!
@MarcoGorelli, @NickCondron, @ShivMunagala, @alexander-beedie, @brandon-b-miller, @coastalwhite, @datenzauberai, @itamarst, @jsarbach, @max-muoto, @nameexhaustion, @orlp, @r-brink, @ritchie46, @stinodego, @thalassemia, @twoertwein and @wence-