Python Polars 0.18.9

🏆 Highlights

• common subexpression elemination (#9632)

⚠️ Deprecations

• Deprecate parsing string inputs as literals for when-then-otherwise (#10122)
• deprecate "connection_uri" → "connection" param in read/write database methods (#10134)
• remove/deprecate cache and its logic (#10066)
• Add date_ranges/time_ranges expression functions (#10005)

🚀 Performance improvements

• speedup mode on sorted data (#10084)
• speedup boolean apply (#10073)
• shrink alp/lp ~2.5x (#10039)

✨ Enhancements

• suggest map_dict instead of lambda x: DICT[x] (#10123)
• enable "inefficient apply" warnings from Series (#10104)
• support writing duration type in json (#10112)
• BytecodeParser can now handle mixed/nested and/or control flow (#10085)
• inline lit(Series).cast(..) to -> lit(Series.cast(..)) (#10092)
• Add ArcTan2 to SQLContext (#9571)
• cse in groupby's (#10062)
• Adds sql CASE statement expressions (#10065)
• Add date_ranges/time_ranges expression functions (#10005)
• comm_subexpr_elim in streaming 'select/with_columns' (#10050)
• add dataframe.flags property (#10037)
• common subexpression elemination (#9632)
• detect and warn about usage of str/int/float python-based casts with apply (#10026)
• detect and warn about usage of json.loads in conjunction with apply (#10023)
• detect and warn about bare numpy functions passed to apply (#10021)
• support bytecode identification/mapping of python string-case functions in UDFs (#10007)
• support bytecode identification of numpy functions in UDFs that we can map to native expressions (#10003)

🐞 Bug fixes

• adjust for null values in str.replace fast path (#10132)
• clear bit settings in list iteration (#10131)
• use row-encoded for struct::is_sorted (#10129)
• fix(rust, python): don't run file-caching in streaming mode (#10117)
• Allow initialize of pl.Array in Dataframe using schema alone (#10100)
• silence Series.apply inefficient apply warning when calling Expr.apply (#10116)
• don't panic if masked out values are invalid in temporal kernels (#10114)
• Fix struct get field by index out of bounds error. (#10097)
• fix ub in simd-json (#10093)
• fix invalid access when groupby rolling produces empty sets (#10109)
• respect null_on_oob=False in list.take when pa… (#10105)
• undo regression in scan_parquet from s3 (#10098)
• fix is_sorted for structs (#10099)
• add file path to io error in scan_csv (#10076)
• fix false positive in parquet stats evaluation (#10087)
• Address .col(regex).exclude() operations not executing. (#10025)
• address an inadvertently shallow-copy issue on underlying PySeries (#10086)
• fix Boolean::isin(null values) (#10074)
• predicate pushdown #10058 (#10071)
• map 'postgres' URI prefix to ADBC 'postgresql' module (#10018)
• Fix weighted quantile for 0 weights (#10051)
• eager time_range/date_range dimensions fix (#9996)

🛠️ Other improvements

• get test_udfs running on all python versions again (#10136)
• temporarily turn off fail-fast so that ubuntu tests run (#10133)
• clarify "clones data" in to_numpy (#10095)
• Refactor when/then/otherwise internals (#9922)
• Properly format Returns sections of docstrings (#10064)
• much-improved Instruction matching for BytecodeParser (#10040)
• add pure-python tests and CI for bytecodeparser (#10027)
• split-out expression translation and instruction-rewrite logic from BytecodeParser (#10012)
• cleans api sections in docs (#10004)
• Bump some dependencies (#9997)
• Add patchelf extra to maturin (#9995)
• restructure all UDF parsing/translation methods into a new BytecodeParser class (#9993)
• Clean up date_range/time_range (#9985)

Thank you to all our contributors for making this release possible!
@MarcoGorelli, @SeanTroyUWO, @alexander-beedie, @c-peters, @cmdlineluser, @jonashaag, @magarick, @mcrumiller, @rikkaka, @ritchie46 and @stinodego