Repository: scikit-learn/scikit-learn
File: examples/release_highlights/plot_release_highlights_1_8_0.py (Python)

Code before:
# Note that array API support is still experimental and must be
# explicitly be enabled both in SciPy and scikit-learn to work properly.
#
# TODO do we want to write a snippet?
# - which estimators would we feature?
# - we don't have PyTorch in doc build for now ...
# - we don't have GPU in the doc build but we could show a snippet with numpy
#   and commented out code to switch to PyToch on GPU
# - alternative: show only highlighted code without executing it?
# - alternative: add link to Colab notebook?

# %%
# Free-threaded CPython 3.14 support
# ----------------------------------
#
# scikit-learn has support for free-threaded CPython, in particular
# free-threaded wheels are available for all of our supported platforms on Python
# 3.14.
#
# Free-threaded (also known as nogil) CPython is a version of CPython that aims at
# enabling efficient multi-threaded use cases by removing the Global Interpreter
# Lock (GIL).
#
# If you want to try out free-threaded Python, the recommendation is to use
# Python 3.14, that has fixed a number of issues compared to Python 3.13. Feel
# free to try free-threaded on your use case and report any issues!
#
# For more details about free-threaded CPython see `py-free-threading doc <https://py-free-threading.github.io>`_,
# in particular `how to install a free-threaded CPython <https://py-free-threading.github.io/installing_cpython/>`_
# and `Ecosystem compatibility tracking <https://py-free-threading.github.io/tracking/>`_.
#
# The long term goal of free-threaded Python is to more efficiently leverage
# multi-core CPUs by using thread workers instead of subprocess workers for parallel
# computation when passing `n_jobs>1` in functions or estimators.
# Efficiency gains are expected by removing the need for inter-process communication.
# Note however that process-based parallelism is still the default joblib backend at
# the time of writing. You can call `joblib.parallel_config(backend="threading")` to
# change the default backend to "threading". Be aware that properly testing that
# everything is running smoothly when doing so is still an ongoing effort and that
# there are open issues to fix before considering making this the default.

# %%
# Temperature scaling in `CalibratedClassifierCV`
# -----------------------------------------------
# Probability calibration of classifiers with temperature scaling is available in
# :class:`calibration.CalibratedClassifierCV` by setting `method = "temperature"`.
# This method is particularly well suited for multiclass problems because it provides
# (better-) calibrated probabilities with just one free parameter, in contrast
# to using a "One-vs-Rest" scheme that adds more parameters for each class.

from sklearn.calibration import CalibratedClassifierCV

Review comment (suggestion):
```suggestion
# To try out scikit-learn's support for free-threading use Python 3.14.
#  Try your use cases and please `report your issues <https://github.com/scikit-learn/scikit-learn/issues/new/choose>`_!
```
Less words mission. Should we link to the "new issue" page? Seems friendly to the user ~~but we don't have a lot of links in this page~~ (edit: I read the next paragraph 😆)

Code after:
# Please refer to the :ref:`array API support<array_api>` page for instructions
# to use scikit-learn with array API compatible libraries such as PyTorch or CuPy.
# Note: Array API support is experimental and must be explicitly enabled both
# in SciPy and scikit-learn.
#
# Here is an excerpt of using a feature engineering preprocessor on the CPU,
# followed by :class:`calibration.CalibratedClassifierCV`
# and :class:`linear_model.RidgeCV` together on a GPU with the help of PyTorch:
#
# .. code-block:: python
#
#     ridge_pipeline_gpu = make_pipeline(
#         # Ensure that all features (including categorical features) are preprocessed
#         # on the CPU and mapped to a numerical representation.
#         feature_preprocessor,
#         # Move the results to the GPU and perform computations there
#         FunctionTransformer(
#             lambda x: torch.tensor(x.to_numpy().astype(np.float32), device="cuda"))
#         ,
#         CalibratedClassifierCV(
#             RidgeClassifierCV(alphas=alphas), method="temperature"
#         ),
#     )
#     with sklearn.config_context(array_api_dispatch=True):
#         cv_results = cross_validate(ridge_pipeline_gpu, features, target)
#
#
# See the `full notebook on Google Colab
# <https://colab.research.google.com/drive/1ztH8gUPv31hSjEeR_8pw20qShTwViGRx?usp=sharing>`_
# for more details. On this particular example, using the Colab GPU vs using a
# single CPU core leads to a 10x speedup which is quite typical for such workloads.

# %%
# Free-threaded CPython 3.14 support
# ----------------------------------
#
# scikit-learn has support for free-threaded CPython, in particular
# free-threaded wheels are available for all of our supported platforms on Python
# 3.14.
#
# We would be very interested by user feedback. Here are a few things you can
# try:
#
# - install free-threaded CPython 3.14, run your favourite
#   scikit-learn script and check that nothing breaks unexpectedly.
#   Note that CPython 3.14 (rather than 3.13) is strongly advised because a
#   number of free-threaded bugs have been fixed since CPython 3.13.
# - if you use some estimators with a `n_jobs` parameter, try changing the
#   default backend to threading with `joblib.parallel_config` as in the
#   snippet below. This could potentially speed-up your code because the
#   default joblib backend is process-based and incurs more overhead than