Python Polars 0.19.0

An upgrade guide is available on our website.

🏆 Highlights

• implementing sink_csv for LazyFrame (#10682)
• Support DataFrame init from queries against users' existing database connections (#10649)
• Rename groupby to group_by (#10656)

💥 Breaking changes

• return f64 for rank when method="average" (#10734)
• Update a lot of error types (#10637)
• Remove deprecated behavior from vertical aggregations (#10602)
• Read/write support for IPC streams in DataFrames (#10606)
• Change behavior of all - fix Kleene logic implementation for all/any (#10564)
• Improve consistency of parsing expression input (#9512)
• allow from_arrow to take a generator of RecordBatches, change error type to TypeError (#10529)
• remove fixed_seed and add pl.set_random_seed (#10388)
• Make arange an alias for int_range (#9983)
• date_range/time_range no longer return a List type (#10526)
• Remove various functionalities deprecated before 0.18 (#10527)
• Improve some error types and messages (#10470)

⚠️ Deprecations

• Rename map to map_batches (#10801)
• Rename GroupBy.apply to map_groups (#10799)
• Rename DataFrame.apply to map_rows (#10797)
• Rename Series/Expr.rolling_apply to rolling_map (#10750)
• Rename Series/Expr.apply to map_elements (#10678)
• Rename groupby to group_by (#10656)
• Deprecate some parameters of cut/qcut (#10484)

🚀 Performance improvements

• parse time zones outside of downcast_iter() in replace_time_zone (#10713)
• use binary abstraction for atan2 (#10588)
• use binary abstraction in pow (#10562)

✨ Enhancements

• activate cse for group_by (again) (#10749)
• implementing sink_csv for LazyFrame (#10682)
• Supports series unique & arg_unique & n_unique for list (#10743)
• repeat_by should also support broadcasting of LHS (#10735)
• deprecate 'use_earliest' argument in favour of 'ambiguous', which can take expressions (#10719)
• is_first also supports numeric list type. (#10727)
• improve slice pushdown in unions (#10723)
• Explicitly implement Protocol for interchange classes (#10688)
• Support min and max strategy for binary & str columns fill null (#10673)
• support broadcasting in list set operations (#10668)
• csv: add schema argument (#10665)
• Support DataFrame init from queries against users' existing database connections (#10649)
• add truncate_ragged_lines (#10660)
• supports cast to list (#10623)
• Update a lot of error types (#10637)
• preserve whitespace in notebook output (#10644)
• Remove deprecated behavior from vertical aggregations (#10602)
• support selector usage in write_excel arguments (#10589)
• Add LazyFrame.collect_async and pl.collect_all_async (#10616)
• Read/write support for IPC streams in DataFrames (#10606)
• propagate null is in is_in and more generic array construction (#10614)
• Change behavior of all - fix Kleene logic implementation for all/any (#10564)
• frame-level cast support (#10504)
• Improve consistency of parsing expression input (#9512)
• Add failed column to cast exception (#10507)
• allow from_arrow to take a generator of RecordBatches, change error type to TypeError (#10529)
• Remove deprecated get_idx_type - use get_index_type instead (#10556)
• Make arange an alias for int_range (#9983)
• date_range/time_range no longer return a List type (#10526)
• Remove various functionalities deprecated before 0.18 (#10527)
• Improve some error types and messages (#10470)
• suggest str.to_datetime instead of apply and stdlib strptime (#10266)

🐞 Bug fixes

• get_single_leaf can't handle Expr::Count (#10790)
• support groupby literal in streaming (#10771)
• ORDER BY on unselected columns (#10752)
• Fix is_in cannot cast list type for float (#10769)
• whitespace CSS in Notebook HTML updated to use pre-wrap instead of pre (#10739)
• only preserve sortedness flag in replace_time_zone when safe (#10738)
• Error on value_counts on column named "counts" (#10737)
• return f64 for rank when method="average" (#10734)
• Keep min/max and arg_min/arg_max consistent. (#10716)
• use time zone from dtype to overwrite output time zone when initialising Series (#10689)
• Cast small int type when scan csv in streaming mode. (#10679)
• raise exception with invalid on arg type for join_asof (#10690)
• Reused input series in rolling_apply should not be orderly (#10694)
• re-sort buffer when update window swap the whole buffer (#10696)
• Set the correct fast_explode flag for ListUtf8ChunkedBuilder (#10684)
• Sorted Utf8Chunked max_str and min_str should consider null value (#10675)
• Correctly handle time zones in write_delta (#10633)
• fix apply for empty series in threading mode (#10651)
• respect 'ignore_errors=False' in csv parser (#10641)
• fix rename + projection pushdown (#10624)
• fix int/float downcast in is_in (#10620)
• Change behavior of all - fix Kleene logic implementation for all/any (#10564)
• Fix serialization for categorical chunked. (#10609)
• Take input_schema to create physical expr for Selection (#10571)
• Clear window cache after evaluate predication expr (#10505)
• Parsing regex col in Expr::Columns (#10551)
• sanitize column naming in boolean ops (#10531)
• Fix write_delta with schema in delta_write_options (#10541)
• remove fixed_seed and add pl.set_random_seed (#10388)
• respect pl.Config options relating to shape, column names, and types when rendering HTML (#10449)

🛠️ Other improvements

• update cargo.lock (#10800)
• Create .venv in repo root (#10789)
• refactored write_database unit tests to properly separate concerns (#10773)
• Fix some broken links / formatting (#10772)
• Document chained when-then behaviour more prominently (#10759)
• Fix test failing due to new adbc release (#10763)
• Unpin connectorx and bump other Python dependencies (#10753)
• add note to testing docs about module import (#10741)
• Clear GitHub Actions caches weekly (#10715)
• Update for new pyarrow 13.0.0 behavior (#10691)
• Fix minor issue with sink_parquet docs (#10669)
• Remove deprecate_renamed_methods util (#10537)
• add "see also" entries to ne/eq_missing and update related examples (#10667)
• fix potential memory leak from usage of inspect.currentframe (#10630)
• give more relevant example for polars.apply (#10631)
• Bump ruff and enable new setting (#10626)
• Add docstrings for Expr.meta namespace (#10617)
• Enforce up-to-date Cargo.lock (#10555)
• deprecate DataFrame.replace (#10600)
• ensure that make requirements fully refreshes unpinned packages/deps (#10591)
• fix out-of-date explain default parameter (#10566)
• Fix expr_dispatch decorator to work on methods with decorators (#10549)
• Fix link to source code (#10542)
• Add title to index page (#10539)
• Disable SIM108 lint (#10519)
• Keep versioned docs (#10500)
• switch to pyo3/maturin-action (#10503)
• Update URLs for dev documentation (#10495)
• Skip failing test (#10496)
• Add version switcher to API reference (#10488)

Thank you to all our contributors for making this release possible!
@JulianCologne, @MarcoGorelli, @Object905, @OndrejSlamecka, @SeanTroyUWO, @VasanthakumarV, @alexander-beedie, @aminalaee, @braaannigan, @c-peters, @ion-elgreco, @lorepozo, @marki259, @mcrumiller, @messense, @orlp, @owrior, @rben01, @reswqa, @ritchie46, @sdamashek, @stinodego, @svaningelgem, @titoeb, @trueb2, @washcycle and @zundertj