# Polars 1.15.0 — Python Polars 1.15.0

- Product: Polars (https://whatsnew.fyi/product/polars)
- Vendor: Polars
- Date: 2024-11-25
- Version: 1.15.0
- Original notes: https://github.com/pola-rs/polars/releases/tag/py-1.15.0
- Permalink: https://whatsnew.fyi/product/polars/releases/1.15.0

What's New is an index, not a publisher: every entry below links to the vendor's own release notes, which are the authoritative source. Entries are labelled where they are hand-curated sample data, pre-releases, or drawn from a secondary source such as a developer blog.

Reuse: the summaries, labels and curation here are © What's New. Quote freely with attribution and a link back; wholesale republication of the corpus is not permitted — terms: https://whatsnew.fyi/terms. The vendors' own release notes remain their publishers'.

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- **added** — Add AhoCorasick backed 'find_many'
- **added** — Add pl.concat_arr to concatenate columns into an Array column
- **added** — Add rounding for Decimal type
- **changed** — Reduce the size of row encoding UTF-8
- **changed** — More efficient row encoding for pl.List
- **changed** — Half the size of Booleans in row encoding
- **changed** — Memoize duplicates in rolling-gb-dyn
- **changed** — Rolling 'iter_lookbehind' breeze through duplicates
- **changed** — Initially trim leading and trailing filtered rows
- **changed** — Speed up starts_with for small prefixes
- **changed** — Auto-enable hive partitioning if hive_schema was given
- **changed** — Support both "iso" and "iso:strict" format options for dt.to_string
- **changed** — Allow Python Enums as dtype inputs
- **changed** — Improved array arithmetic support
- **changed** — Improve export from 2D Array dtype columns to PyTorch Tensors (to_torch) and Jax Arrays (to_jax)
- **fixed** — Fix Decimal type fill_null
- **fixed** — Fix panic on schema merge for prefiltering
- **fixed** — Fix lazy frame join expression
- **fixed** — Fix gather_every for Scalar

##### 🚀 Performance improvements

- Reduce the size of row encoding UTF-8 (#19911)
- Memoize duplicates in rolling-gb-dyn (#19939)
- More efficient row encoding for `pl.List` (#19907)
- Half the size of Booleans in row encoding (#19927)
- Rolling 'iter\_lookbehind' breeze through duplicates (#19922)
- Initially trim leading and trailing filtered rows (#19850)

##### ✨ Enhancements

- Catch use of 'polars' in `to_string` for non-Duration dtypes and raise an informative error (#19977)
- Add AhoCorasick backed 'find\_many' (#19952)
- Allow Python Enums as dtype inputs (#19926)
- Speed up starts\_with for small prefixes (#19904)
- Auto-enable hive partitioning if hive\_schema was given (#19902)
- Add `pl.concat_arr` to concatenate columns into an Array column (#19881)
- Support both "iso" and "iso:strict" format options for `dt.to_string` (#19840)
- Add rounding for Decimal type (#19760)
- Improved array arithmetic support (#19837)

##### 🐞 Bug fixes

- Fix Decimal type fill\_null (#19981)
- Fix panic on schema merge for prefiltering (#19972)
- Fix lazy frame join expression (#19974)
- Fix `gather_every` for `Scalar` (#19964)
- Toggle 'fast\_unique' on new\_from\_index (#19956)
- Parse uppercase config keys (#19852)
- Raise proper error message when too small interval is passed to datetime\_range (#19955)
- Fix scalar object (#19940)
- Raise InvalidOperationError for invalid float to decimal casts (e.g. Inf, NaN) (#19938)
- Address indexing edge-case with `numpy` arrays (#19895)
- Fix panic with combination of hive and parquet prefiltering (#19905)
- Fix panic when joining with empty frame (debug only) (#19896)
- Fix incorrect result from inequality filter after join on LazyFrame (#19898)
- Misleading `ShapeError` error message on dataframe creation (#19901)
- Fix panic with empty delta scan, or empty parquet scan with a provided schema (#19884)
- Ensure type object of inputs for cached any-value conversion functions are kept alive (#19866)
- Improve export from 2D Array dtype columns to PyTorch Tensors (`to_torch`) and Jax Arrays (`to_jax`) (#19862)
- Fix panic using `scan_parquet().with_row_index()` with hive partitioning enabled (#19865)
- Improve histogram bin logic (#18761)
- Raise informative error instead of panicking for list arithmetic on some invalid dtypes (#19841)
- Properly handle Zero-Field Structs in row encoding (#19846)
- Incorrect explode schema for `LazyFrame.explode()` (#19860)
- DataFrame `rows_by_key` returning key tuples with elements in wrong order (#19486)
- Ensure `List` element truncation ellipses respect `ASCII*` table formats (#19835)

##### 📖 Documentation

- Remove duplicate sentence in `Series.bottom_k` docstring (#19947)
- Complete parameters description and add an example for `clip()` (#19875)
- Fix some warnings during docs build (#19848)

##### 📦 Build system

- Use public windows runners in python release (#19982)
- Add windows-aarch64 to python binaries (#19966)

##### 🛠️ Other improvements

- Minor non-breaking space (` `) tweak for HTML rendering (#19864)
- Implement nested row encoding / decoding (#19874)
- Switch back to PyO3 0.22 (#19851)
- Adjust flaky `with_columns` test (#19844)
- Add proper tests for row encoding (#19843)

Thank you to all our contributors for making this release possible!
@MarcoGorelli, @alexander-beedie, @barak1412, @coastalwhite, @etiennebacher, @ion-elgreco, @itamarst, @lukemanley, @mcrumiller, @mhogervo, @nameexhaustion, @orlp, @ritchie46, @stijnherfst and @stinodego