What's Changed

• partial support for list arithmetic by @ritchie46 in https://github.com/pola-rs/polars/pull/3307
• shuffle sample option by @ritchie46 in https://github.com/pola-rs/polars/pull/3308
• improve predicate pushdown by @ritchie46 in https://github.com/pola-rs/polars/pull/3313
• Improve partitioned agg by @ritchie46 in https://github.com/pola-rs/polars/pull/3314
• list to struct by @ritchie46 in https://github.com/pola-rs/polars/pull/3317
• oncecell in favor of lazy_static by @ritchie46 in https://github.com/pola-rs/polars/pull/3319
• Update cummax documentation by @briandk in https://github.com/pola-rs/polars/pull/3323
• scan pyarrow dataset by @ritchie46 in https://github.com/pola-rs/polars/pull/3327
• fix panic in csv parser by @ritchie46 in https://github.com/pola-rs/polars/pull/3339
• implement anyvalue -> datatype for all variants by @ritchie46 in https://github.com/pola-rs/polars/pull/3340
• remove badge by @ritchie46 in https://github.com/pola-rs/polars/pull/3341
• Added PartitionedWriter for disk partitioning. by @illumination-k in https://github.com/pola-rs/polars/pull/3331
• Fast json by @universalmind303 in https://github.com/pola-rs/polars/pull/3324
• add hash to rust expressions by @ritchie46 in https://github.com/pola-rs/polars/pull/3350
• serde for group options by @elferherrera in https://github.com/pola-rs/polars/pull/3349
• Check if length of index in pivot operation is non-zero. Fixes: #3343. by @ghuls in https://github.com/pola-rs/polars/pull/3346
• improve agg_list performance of chunked numerical data by @ritchie46 in https://github.com/pola-rs/polars/pull/3351
• Fix init of DataFrame with empty dataset (eg:"[]") and column/schema typedefs by @alexander-beedie in https://github.com/pola-rs/polars/pull/3353
• rechunk on default sort and groupby by @ritchie46 in https://github.com/pola-rs/polars/pull/3354
• more partitioned groupby by @ritchie46 in https://github.com/pola-rs/polars/pull/3355
• Add extension_module in python example by @Maxyme in https://github.com/pola-rs/polars/pull/3358
• allow join on same cat source by @ritchie46 in https://github.com/pola-rs/polars/pull/3363
• fix rename same name by @ritchie46 in https://github.com/pola-rs/polars/pull/3364
• initial timezone support by @ritchie46 in https://github.com/pola-rs/polars/pull/3357
• pivot index maintain logical type by @ritchie46 in https://github.com/pola-rs/polars/pull/3367
• use array_ref in favor of chunks by @ritchie46 in https://github.com/pola-rs/polars/pull/3368
• entropy normalization arg by @ritchie46 in https://github.com/pola-rs/polars/pull/3369
• categorical keep type in comparisson by @ritchie46 in https://github.com/pola-rs/polars/pull/3370
• rechunk in asof and allow concat to empty df by @ritchie46 in https://github.com/pola-rs/polars/pull/3376
• improve overflow of numeric mean by @ritchie46 in https://github.com/pola-rs/polars/pull/3377
• fix parquet stats by @ritchie46 in https://github.com/pola-rs/polars/pull/3378
• delay rechunk optimization by @ritchie46 in https://github.com/pola-rs/polars/pull/3381
• Allow Z in native strpttime by @ritchie46 in https://github.com/pola-rs/polars/pull/3382
• more partitioned aggregators by @ritchie46 in https://github.com/pola-rs/polars/pull/3385
• improve partition_by by @ritchie46 in https://github.com/pola-rs/polars/pull/3386
• Add overload support to partition_by. by @ghuls in https://github.com/pola-rs/polars/pull/3388
• Check if some arguments for read_csv and scan_csv got a 1 byte input. by @ghuls in https://github.com/pola-rs/polars/pull/3389
• fix rayon SO in partition_by by @ritchie46 in https://github.com/pola-rs/polars/pull/3391
• fix bug in predicate pushdown on dependent predicates by @ritchie46 in https://github.com/pola-rs/polars/pull/3394
• fix predicate pushdown for predicates that do aggregations by @ritchie46 in https://github.com/pola-rs/polars/pull/3396
• cumulative_eval by @ritchie46 in https://github.com/pola-rs/polars/pull/3400
• ensure that Cast expressions first updates groups before it flattens by @ritchie46 in https://github.com/pola-rs/polars/pull/3401
• improve and simplify ternary aggregation by @ritchie46 in https://github.com/pola-rs/polars/pull/3403
• fix explode empty df by @ritchie46 in https://github.com/pola-rs/polars/pull/3405
• Improve list builders, iteration and construction by @ritchie46 in https://github.com/pola-rs/polars/pull/3419
• feature gate timezones by @ritchie46 in https://github.com/pola-rs/polars/pull/3422
• fix cumulative_eval on window expressions by @ritchie46 in https://github.com/pola-rs/polars/pull/3421
• csv allow only header and fix lazy rename by @ritchie46 in https://github.com/pola-rs/polars/pull/3423
• upgrade arrow by @ritchie46 in https://github.com/pola-rs/polars/pull/3425
• infer dtype of empty list in recursive list construction & fix struct.arr take by @ritchie46 in https://github.com/pola-rs/polars/pull/3433
• fix struct list concat by @ritchie46 in https://github.com/pola-rs/polars/pull/3435
• csv parser fallback on chrono if datetime pattern fails by @ritchie46 in https://github.com/pola-rs/polars/pull/3436
• improve rolling_quantile kernel (no nulls) ~28x by @ritchie46 in https://github.com/pola-rs/polars/pull/3437
• improve rolling_{min/max/sum/mean} prerformance ~3.4x by @ritchie46 in https://github.com/pola-rs/polars/pull/3444
• struct add chunk and impl reverse by @ritchie46 in https://github.com/pola-rs/polars/pull/3445
• fix struct equality by @ritchie46 in https://github.com/pola-rs/polars/pull/3446
• Struct error on different dict orders by @ritchie46 in https://github.com/pola-rs/polars/pull/3447
• Inherit Exception in fallback exception classes by @adamgreg in https://github.com/pola-rs/polars/pull/3450
• Struct creations/append/extend stricter schema by @ritchie46 in https://github.com/pola-rs/polars/pull/3454
• don't allow predicate pushdown if compared column is being coerced by @ritchie46 in https://github.com/pola-rs/polars/pull/3457
• improve rolling_min/max for columns with null values by @ritchie46 in https://github.com/pola-rs/polars/pull/3458
• Improve rolling_sum/rolling_mean for windows with null values. by @ritchie46 in https://github.com/pola-rs/polars/pull/3466
• explode series after slide fast path by @ritchie46 in https://github.com/pola-rs/polars/pull/3467
• Improve struct by @ritchie46 in https://github.com/pola-rs/polars/pull/3468
• improve rolling_var performance by @ritchie46 in https://github.com/pola-rs/polars/pull/3470
• power by expression and improve rust lazy ergonomics by @ritchie46 in https://github.com/pola-rs/polars/pull/3475
• add specialized rolling_std kernel by @ritchie46 in https://github.com/pola-rs/polars/pull/3476
• fix null commutativity by @ritchie46 in https://github.com/pola-rs/polars/pull/3479
• use anyvalue if first apply list result is empty by @ritchie46 in https://github.com/pola-rs/polars/pull/3480
• Added describe method to rust library by @glennpierce in https://github.com/pola-rs/polars/pull/3320
• Groupby Optimization for sorted keys: ~15x perf gain. by @ritchie46 in https://github.com/pola-rs/polars/pull/3489
• make cat merge fallible and loossen restrictions on categorical appends by @ritchie46 in https://github.com/pola-rs/polars/pull/3491
• Fix LazyFrame.join_asof documentation reference by @adamgreg in https://github.com/pola-rs/polars/pull/3493
• feat: support pl.Time in Series.str.strptime by @fsimkovic in https://github.com/pola-rs/polars/pull/3496
• str().extract_all / str().count_match by @ritchie46 in https://github.com/pola-rs/polars/pull/3507
• add apply to cookbooks by @ritchie46 in https://github.com/pola-rs/polars/pull/3504
• support all arrow dictionary keys < 64 bit by @ritchie46 in https://github.com/pola-rs/polars/pull/3508
• fix accidental quadratic behavior in rolling_groupby by @ritchie46 in https://github.com/pola-rs/polars/pull/3510
• Fix some unit test deprecation warnings by @adamgreg in https://github.com/pola-rs/polars/pull/3503
• Experimental Allow rolling_<agg> expressions to determine window size by another {Date, Datetime} series. by @ritchie46 in https://github.com/pola-rs/polars/pull/3514
• use specialize kernels in rolling_groupby aggregation ~10x perf gain (window of 100 elements) by @ritchie46 in https://github.com/pola-rs/polars/pull/3515
• reduce probability of quadratic behavior in min/max rolling by @ritchie46 in https://github.com/pola-rs/polars/pull/3516
• adjust for kleene logic in drop_na by @ritchie46 in https://github.com/pola-rs/polars/pull/3529
• fix aggregation of empty list by @ritchie46 in https://github.com/pola-rs/polars/pull/3527
• fix sorting of chunked numeric arrays by @ritchie46 in https://github.com/pola-rs/polars/pull/3528
• adjust for kleene logic in drop_na by @ritchie46 in https://github.com/pola-rs/polars/pull/3530
• Improve rolling min max by @ritchie46 in https://github.com/pola-rs/polars/pull/3531
• fix null aggregation edge case by @ritchie46 in https://github.com/pola-rs/polars/pull/3536
• allow concat/append expressions by @ritchie46 in https://github.com/pola-rs/polars/pull/3541
• make sort by multiple columns parallel by @ritchie46 in https://github.com/pola-rs/polars/pull/3549
• allow more aggregations on dtype duration by @ritchie46 in https://github.com/pola-rs/polars/pull/3550
• use first series to validate length by @ritchie46 in https://github.com/pola-rs/polars/pull/3551
• Raise a more helpful TypeError when trying to subscript a LazyFrame. by @ghuls in https://github.com/pola-rs/polars/pull/3554
• Readability Fixes r2 by @ryanrussell in https://github.com/pola-rs/polars/pull/3556
• add count_match, extract_all to python ref guide by @ritchie46 in https://github.com/pola-rs/polars/pull/3558
• fill_null limits by @ritchie46 in https://github.com/pola-rs/polars/pull/3559
• test sortedness propagation by @ritchie46 in https://github.com/pola-rs/polars/pull/3560
• update boolean aggregates and ensure they return IdxSize by @ritchie46 in https://github.com/pola-rs/polars/pull/3563
• Improve parse_lines error message. by @ghuls in https://github.com/pola-rs/polars/pull/3569
• sorted_merge_join by @ritchie46 in https://github.com/pola-rs/polars/pull/3505
• Rust Readability Improvements by @ryanrussell in https://github.com/pola-rs/polars/pull/3573
• fix invalid fast path of sorted joins and improve sortedness propagation by @ritchie46 in https://github.com/pola-rs/polars/pull/3577
• prevent expensive type coercion in expression and fix when->then->oth… by @ritchie46 in https://github.com/pola-rs/polars/pull/3579
• Updated the fmt feature flag error message by @TheDan64 in https://github.com/pola-rs/polars/pull/3586
• Fix u16 Series formatting. by @ghuls in https://github.com/pola-rs/polars/pull/3584
• update arrow to crates.io: ~2x json parsing improvement by @ritchie46 in https://github.com/pola-rs/polars/pull/3588

New Contributors

• @kianmeng made their first contribution in https://github.com/pola-rs/polars/pull/3311
• @briandk made their first contribution in https://github.com/pola-rs/polars/pull/3323
• @EwoutH made their first contribution in https://github.com/pola-rs/polars/pull/3352
• @adamgreg made their first contribution in https://github.com/pola-rs/polars/pull/3450
• @ryanrussell made their first contribution in https://github.com/pola-rs/polars/pull/3488
• @fsimkovic made their first contribution in https://github.com/pola-rs/polars/pull/3496
• @chitralverma made their first contribution in https://github.com/pola-rs/polars/pull/3578
• @TheDan64 made their first contribution in https://github.com/pola-rs/polars/pull/3586

Full Changelog: https://github.com/pola-rs/polars/compare/rust-polars-v0.21.1...rust-polars-v0.22.1