v0.14.0

Summary

This release updates the supported Python range (drops 3.9, adds 3.13) and adds compatibility with scipy 1.16. It continues the Narwhals integration work in the postprocessing module and GroupFeature, fixes a polars dataframe-interchange deprecation, and corrects the handling of degenerate sensitive feature values in PrototypeRepresentationLearner.

Bug fixes

• Fixed handling of single-group (degenerate) sensitive features in PrototypeRepresentationLearner.fit, which previously failed during the fairness-error computation: #1626 by BALOGUN DAVID TAIWO.

• Changed GridSearch.fit to return self, matching the scikit-learn estimator convention: #1622 by Nithin.

• Fixed a polars dataframe-interchange protocol deprecation in AnnotatedMetricFunction and corrected the 1D-array branch at the same time: #1639 by Tahar Allouche.

• Added a MANIFEST.in so that requirements*.txt are included in the source distribution, and switched the build pipeline to the PEP 517 build frontend: #1628 by Christian Heimes.

• Excluded the test and test_othermlpackages directories from the fairlearn packaging distribution: #1644 by Parul Gupta.

Narwhals integration

• Made postprocessing/_tradeoff_curve_utilities.py dataframe agnostic through Narwhals: #1553 by Francesco Bruzzesi.

• Made GroupFeature dataframe agnostic through Narwhals: #1546 by Francesco Bruzzesi.

Documentation

• Added a GridSearch algorithm overview and usage example to the reductions user guide: #1622 by Nithin.

• Added a usage example for mean_prediction in the advanced MetricFrame guide: #1637 by @3Paradox.

• Improved docstrings for base metrics, DisaggregatedResult methods, and MetricFrame group methods: #1621 by Nithin.

• Added versionadded and versionchanged directives to the public docstrings in fairlearn.metrics: #1640 by Bader.

• Corrected the true-positive-rate formula in the equal_opportunity_difference and equal_opportunity_ratio docstrings (from E[h(X) | A=a] to P[h(X)=1 | A=a, Y=1]): #1605 by Ophy Boamah Ampoh.

• Removed the outdated Fairlearn repository overview page from the contributor guide: #1606 by @Anish8800.

• Fixed minor spacing and punctuation in docs/user_guide/fairness_in_machine_learning.rst: #1611 by @Anish8800.

• Updated the Maintainers link in the README to point directly to the Maintainers section of the website instead of the general About page: #1601 by @itz8bitstudios.

Other improvements

• Removed support for Python 3.9 and added support for Python 3.13: #1592 by Tamara Atanasoska.

• Added support for scipy 1.16: #1596 by Tamara Atanasoska.

• Raised the minimum supported scikit-learn to 1.5.0 and the pinned torch in requirements-min.txt to 2.8.0 to clear Dependabot security advisories: #1645 by Roman Lutz.

• Removed an unused name argument from GroupFeature: #1599 by Tahar Allouche.

• Avoided a sys module patching leak in the test suite: #1600 by Tahar Allouche.

• Removed a Pillow deprecation warning by requiring matplotlib>=3.10.5: #1618 by Ibim Braide.

• Fixed a DataFrame fragmentation PerformanceWarning in the reductions module: #1631 by BALOGUN DAVID TAIWO.

• Closed Matplotlib figures before/after tests to avoid a deprecation warning: #1603 by @lolashaffy.

• Sped up the reductions test suite: #1574 by Tahar Allouche.

• Sped up the preprocessing test suite: #1573 by Tahar Allouche.

• Sped up the metrics test suite: #1572 by Tahar Allouche.

• Improved unit tests for PrototypeRepresentationLearner: stopped overriding parametrized sensitive_features values inside the test bodies and added coverage for multi-dimensional sensitive features: #1623 by Tahar Allouche.

• Cached OpenML datasets in CI runs: #1598 by Francesco Bruzzesi.

• Added a Narwhals pytest marker: #1597 by Francesco Bruzzesi.