# Polars 1.18.0 — Python Polars 1.18.0

- Product: Polars (https://whatsnew.fyi/product/polars)
- Vendor: Polars
- Date: 2024-12-24
- Version: 1.18.0
- Original notes: https://github.com/pola-rs/polars/releases/tag/py-1.18.0
- Permalink: https://whatsnew.fyi/product/polars/releases/1.18.0

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 new Int128Type
- **added** — Support loading data from multiple Excel/ODS workbooks
- **added** — Add drop_empty_cols parameter for read_excel and read_ods
- **added** — Add FirstArgLossless supertype
- **added** — Add dt.replace
- **added** — Polars build for Pyodide
- **added** — Add Azure credential provider using DefaultAzureCredential()
- **added** — Add env var to ignore file cache allocate error
- **added** — Add bin.reinterpret
- **added** — Add cat.len_chars and cat.len_bytes
- **added** — Add skip_lines for CSV
- **changed** — Always resolve dynamic types in schema
- **changed** — Enable joins between compatible differing numeric key columns
- **changed** — Cache dtype on ExprIR
- **changed** — Serialize DataFrame/Series using IPC in serde
- **changed** — Allow subtraction of time dtype columns
- **changed** — Allow decoding of non-Polars arrow dictionaries in Arrow and Parquet
- **changed** — Expose AexprArena
- **changed** — Update pyo3 and numpy crates to version 0.23
- **fixed** — Fix nullable object in map_elements
- **fixed** — Properly handle to_physical_repr of nested types

##### 🏆 Highlights

- Add new `Int128Type`  (#20232)

##### 🚀 Performance improvements

- Order observability optimizations (#20396)
- Purge ChunkedArray Metadata (#20371)
- Explicit transpose in new-streaming equi-join finalize (#20363)
- Cache dtype on ExprIR (#20331)
- Lower overhead for `BytecodeParser` on introspection of incompatible UDFs (#20280)

##### ✨ Enhancements

- Always resolve dynamic types in schema (#20406)
- Support loading data from multiple Excel/ODS workbooks (#20404)
- Add "drop_empty_cols" parameter for `read_excel` and `read_ods` (#20430)
- Order observability optimizations (#20396)
- Add FirstArgLossless supertype (#20394)
- Add `dt.replace` (#19708)
- Polars build for Pyodide (#20383)
- Add Azure credential provider using `DefaultAzureCredential()` (#20384)
- Add env var to ignore file cache allocate error (#20356)
- Enable joins between compatible differing numeric key columns (#20332)
- Cache dtype on ExprIR (#20331)
- Serialize DataFrame/Series using IPC in serde (#20266)
- Improve error message on SchemaError (#20326)
- Use better error messages when opening files (#20307)
- Add 'skip\_lines' for CSV (#20301)
- Allow subtraction of time dtype columns (#20300)
- Add `bin.reinterpret` (#20263)
- Allow decoding of non-Polars arrow dictionaries in Arrow and Parquet (#20248)
- Streamline creation of empty frame from `Schema` (#20267)
- Add `cat.len_chars` and `cat.len_bytes` (#20211)
- Expose AexprArena (#20230)

##### 🐞 Bug fixes

- Fix nullable object in map\_elements (#20422)
- Properly handle `to_physical_repr` of nested types (#20413)
- Properly raise UDF errors (#20417)
- Workaround for `mmap` crash under Emscripten (#20418)
- Fix using `new_columns` in `scan_csv` with compressed file (#20412)
- Fix return type of `Series.dt.add_business_days` (#20402)
- Fix decimal series dispatch (#20400)
- Fix decimal arithmetic schema (#20398)
- Raise on categorical search\_sorted (#20395)
- Fix plotting f-strings and docstrings (#20399)
- Don't try to load non-existend List/FSL statistics (#20388)
- Propagate nulls for float methods on all numeric types (#20386)
- Add env var to ignore file cache allocate error (#20356)
- Flip order on right join (#20358)
- Correctly parse special float values in `from_repr` (#20351)
- Fix incorrect object store caching for ADLS URI (#20357)
- Use the same encoding for nullable as non-nullable arrays (#20323)
- Improve error message on SchemaError (#20326)
- Boolean optional slice pushdown (#20315)
- Properly handle `from_physical` for List/Array (#20311)
- Ignore quotes in csv comments (#20306)
- Ensure pl.datetime returns empty column when input columns are empty (#20278)
- Ensure output height does not change on lazy projection pushdown with aggregations (#20223)
- Fix error writing on Windows to locations outside of C drive (#20245)
- Incorrect comparison in some cases with filtered list/array columns (#20243)
- Ensure height is maintained in SQL `SELECT 1 FROM` (#20241)
- Properly account for updated Categorical in .unique() kernel (#20235)

##### 📖 Documentation

- Improve docstring clarity (#20416)
- Update GPU engine installation instructions to remove `--extra-index-url` from CUDA 12 packages (#20381)
- Remove Plugins overview page without information (#20348)
- Small fixes/clarifications in user guide (#20335)
- Improve docs about NaN (#20310)
- Fix substr function param definition (#19054)
- Include parquet options in BigQuery I/O write sample (#20292)
- Fix typo in `fork` warning (#20258)

##### 📦 Build system

- Add `project.dynamic = ["version"]` to pyproject.toml (#20345)
- Update `pyo3` and `numpy` crates to version `0.23` (#20111)
- Build wheels for ARM Windows in Python release workflow (#20247)

##### 🛠️ Other improvements

- Enable masked out list, struct and array elements in parametric tests (#20365)
- Move hive partitioning/multi-file handling outside of reader

_[Truncated at 4000 characters — full notes: https://github.com/pola-rs/polars/releases/tag/py-1.18.0]_