Polars: py-0.20.26 Release

⚠️ Deprecations

• Deprecate allow_infinities and null_probability args to parametric test strategies (#16183)

🚀 Performance improvements

• Avoid needless copy when converting chunked Series to NumPy (#16178)
• 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)

✨ Enhancements

• Clarify to_torch "features" and "label" parameter behaviour when return type is not "dataset" (#16218)
• Native CSV file list reading (#16180)
• Register memory mapped files and raise when written to (#16208)
• Implement support for Struct types in parametric tests (#16197)
• Enable Null datatype and null values by default in parametric testing (#16192)
• Support Enum types in parametric testing (#16188)
• 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)
• Overhaul parametric test implementations and update Hypothesis to latest version (#16062)
• Avoid an extra copy when converting Boolean Series to writable NumPy array (#16164)
• Allow implicit string → temporal conversion in SQL comparisons (#15958)
• Add run-length encoding to Parquet writer (#16125)
• Support passing instantiated adbc/alchemy connection objects to write_database (#16099)
• Add top-level nth(n) method, to go with existing first and last (#16112)

🐞 Bug fixes

• 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)
• Respect dtype and strict in pl.Series's constructor for pyarrow arrays, numpy arrays, and pyarrow-backed pandas (#15962)
• Ensure hex and bitstring literals work inside SQL IN clauses (#16101)

📖 Documentation

• Add examples for multiple Series functions (#16172)
• Add deprecated messages to cumfold and cumreduce (#16173)
• StringNameSpace.replace_all docstring (#16169)
• Explain how Polars floor division differs from Python (#16054)
• Clarify arrow usage (#16152)
• Add example to polars.Series.flags (#16123)

🛠️ Other improvements

• Switch over some of the custom Python date/time conversions to native PyO3 conversions (#16203)
• move describe to IR instead of DSL (#16191)
• More PyO3 0.21 Bound<> APIs, and finally disable gil-refs backwards compat feature on pyo3 crate (#16143)
• Move hypothesis tests into unit test module (#16185)
• Remove unused code (#16175)
• Update plugin example to PyO3 0.21 (#16157)
• Return correct temporal type from Rust in to_numpy (#14353)
• Create NumPy view for Datetime/Duration Series on the Rust side (#16148)
• Don't override CSV reader encoding with lossy UTF-8 (#16151)
• Continue converting to PyO3 0.21 Bound<> APIs (#16081)

Thank you to all our contributors for making this release possible! @MarcoGorelli, @YichiZhang0613, @alexander-beedie, @bertiewooster, @coastalwhite, @dangotbanned, @itamarst, @janpipek, @jrycw, @luke396, @nameexhaustion, @pydanny, @ritchie46, @stinodego, @thalassemia and @tharunsuresh-code