sklearn/doc/whats_new/v0.20.rst

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.. include:: _contributors.rst
.. currentmodule:: sklearn
============
Version 0.20
============
.. warning::
Version 0.20 is the last version of scikit-learn to support Python 2.7 and Python 3.4.
Scikit-learn 0.21 will require Python 3.5 or higher.
.. include:: changelog_legend.inc
.. _changes_0_20_4:
Version 0.20.4
==============
**July 30, 2019**
This is a bug-fix release with some bug fixes applied to version 0.20.3.
Changelog
---------
The bundled version of joblib was upgraded from 0.13.0 to 0.13.2.
:mod:`sklearn.cluster`
..............................
- |Fix| Fixed a bug in :class:`cluster.KMeans` where KMeans++ initialisation
could rarely result in an IndexError. :issue:`11756` by `Joel Nothman`_.
:mod:`sklearn.compose`
.......................
- |Fix| Fixed an issue in :class:`compose.ColumnTransformer` where using
DataFrames whose column order differs between :func:``fit`` and
:func:``transform`` could lead to silently passing incorrect columns to the
``remainder`` transformer.
:pr:`14237` by `Andreas Schuderer <schuderer>`.
:mod:`sklearn.decomposition`
............................
- |Fix| Fixed a bug in :class:`cross_decomposition.CCA` improving numerical
stability when `Y` is close to zero. :pr:`13903` by `Thomas Fan`_.
:mod:`sklearn.model_selection`
..............................
- |Fix| Fixed a bug where :class:`model_selection.StratifiedKFold`
shuffles each class's samples with the same ``random_state``,
making ``shuffle=True`` ineffective.
:issue:`13124` by :user:`Hanmin Qin <qinhanmin2014>`.
:mod:`sklearn.neighbors`
........................
- |Fix| Fixed a bug in :class:`neighbors.KernelDensity` which could not be
restored from a pickle if ``sample_weight`` had been used.
:issue:`13772` by :user:`Aditya Vyas <aditya1702>`.
.. _changes_0_20_3:
Version 0.20.3
==============
**March 1, 2019**
This is a bug-fix release with some minor documentation improvements and
enhancements to features released in 0.20.0.
Changelog
---------
:mod:`sklearn.cluster`
......................
- |Fix| Fixed a bug in :class:`cluster.KMeans` where computation was single
threaded when `n_jobs > 1` or `n_jobs = -1`.
:issue:`12949` by :user:`Prabakaran Kumaresshan <nixphix>`.
:mod:`sklearn.compose`
......................
- |Fix| Fixed a bug in :class:`compose.ColumnTransformer` to handle
negative indexes in the columns list of the transformers.
:issue:`12946` by :user:`Pierre Tallotte <pierretallotte>`.
:mod:`sklearn.covariance`
.........................
- |Fix| Fixed a regression in :func:`covariance.graphical_lasso` so that
the case `n_features=2` is handled correctly. :issue:`13276` by
:user:`Aurélien Bellet <bellet>`.
:mod:`sklearn.decomposition`
............................
- |Fix| Fixed a bug in :func:`decomposition.sparse_encode` where computation was single
threaded when `n_jobs > 1` or `n_jobs = -1`.
:issue:`13005` by :user:`Prabakaran Kumaresshan <nixphix>`.
:mod:`sklearn.datasets`
............................
- |Efficiency| :func:`sklearn.datasets.fetch_openml` now loads data by
streaming, avoiding high memory usage. :issue:`13312` by `Joris Van den
Bossche`_.
:mod:`sklearn.feature_extraction`
.................................
- |Fix| Fixed a bug in :class:`feature_extraction.text.CountVectorizer` which
would result in the sparse feature matrix having conflicting `indptr` and
`indices` precisions under very large vocabularies. :issue:`11295` by
:user:`Gabriel Vacaliuc <gvacaliuc>`.
:mod:`sklearn.impute`
.....................
- |Fix| add support for non-numeric data in
:class:`sklearn.impute.MissingIndicator` which was not supported while
:class:`sklearn.impute.SimpleImputer` was supporting this for some
imputation strategies.
:issue:`13046` by :user:`Guillaume Lemaitre <glemaitre>`.
:mod:`sklearn.linear_model`
...........................
- |Fix| Fixed a bug in :class:`linear_model.MultiTaskElasticNet` and
:class:`linear_model.MultiTaskLasso` which were breaking when
``warm_start = True``. :issue:`12360` by :user:`Aakanksha Joshi <joaak>`.
:mod:`sklearn.preprocessing`
............................
- |Fix| Fixed a bug in :class:`preprocessing.KBinsDiscretizer` where
``strategy='kmeans'`` fails with an error during transformation due to unsorted
bin edges. :issue:`13134` by :user:`Sandro Casagrande <SandroCasagrande>`.
- |Fix| Fixed a bug in :class:`preprocessing.OneHotEncoder` where the
deprecation of ``categorical_features`` was handled incorrectly in
combination with ``handle_unknown='ignore'``.
:issue:`12881` by `Joris Van den Bossche`_.
- |Fix| Bins whose width are too small (i.e., <= 1e-8) are removed
with a warning in :class:`preprocessing.KBinsDiscretizer`.
:issue:`13165` by :user:`Hanmin Qin <qinhanmin2014>`.
:mod:`sklearn.svm`
..................
- |FIX| Fixed a bug in :class:`svm.SVC`, :class:`svm.NuSVC`, :class:`svm.SVR`,
:class:`svm.NuSVR` and :class:`svm.OneClassSVM` where the ``scale`` option
of parameter ``gamma`` is erroneously defined as
``1 / (n_features * X.std())``. It's now defined as
``1 / (n_features * X.var())``.
:issue:`13221` by :user:`Hanmin Qin <qinhanmin2014>`.
Code and Documentation Contributors
-----------------------------------
With thanks to:
Adrin Jalali, Agamemnon Krasoulis, Albert Thomas, Andreas Mueller, Aurélien
Bellet, bertrandhaut, Bharat Raghunathan, Dowon, Emmanuel Arias, Fibinse
Xavier, Finn O'Shea, Gabriel Vacaliuc, Gael Varoquaux, Guillaume Lemaitre,
Hanmin Qin, joaak, Joel Nothman, Joris Van den Bossche, Jérémie Méhault, kms15,
Kossori Aruku, Lakshya KD, maikia, Manuel López-Ibáñez, Marco Gorelli,
MarcoGorelli, mferrari3, Mickaël Schoentgen, Nicolas Hug, pavlos kallis, Pierre
Glaser, pierretallotte, Prabakaran Kumaresshan, Reshama Shaikh, Rohit Kapoor,
Roman Yurchak, SandroCasagrande, Tashay Green, Thomas Fan, Vishaal Kapoor,
Zhuyi Xue, Zijie (ZJ) Poh
.. _changes_0_20_2:
Version 0.20.2
==============
**December 20, 2018**
This is a bug-fix release with some minor documentation improvements and
enhancements to features released in 0.20.0.
Changed models
--------------
The following estimators and functions, when fit with the same data and
parameters, may produce different models from the previous version. This often
occurs due to changes in the modelling logic (bug fixes or enhancements), or in
random sampling procedures.
- :mod:`sklearn.neighbors` when ``metric=='jaccard'`` (bug fix)
- use of ``'seuclidean'`` or ``'mahalanobis'`` metrics in some cases (bug fix)
Changelog
---------
:mod:`sklearn.compose`
......................
- |Fix| Fixed an issue in :func:`compose.make_column_transformer` which raises
unexpected error when columns is pandas Index or pandas Series.
:issue:`12704` by :user:`Hanmin Qin <qinhanmin2014>`.
:mod:`sklearn.metrics`
......................
- |Fix| Fixed a bug in :func:`metrics.pairwise_distances` and
:func:`metrics.pairwise_distances_chunked` where parameters ``V`` of
``"seuclidean"`` and ``VI`` of ``"mahalanobis"`` metrics were computed after
the data was split into chunks instead of being pre-computed on whole data.
:issue:`12701` by :user:`Jeremie du Boisberranger <jeremiedbb>`.
:mod:`sklearn.neighbors`
........................
- |Fix| Fixed `sklearn.neighbors.DistanceMetric` jaccard distance
function to return 0 when two all-zero vectors are compared.
:issue:`12685` by :user:`Thomas Fan <thomasjpfan>`.
:mod:`sklearn.utils`
....................
- |Fix| Calling :func:`utils.check_array` on `pandas.Series` with categorical
data, which raised an error in 0.20.0, now returns the expected output again.
:issue:`12699` by `Joris Van den Bossche`_.
Code and Documentation Contributors
-----------------------------------
With thanks to:
adanhawth, Adrin Jalali, Albert Thomas, Andreas Mueller, Dan Stine, Feda Curic,
Hanmin Qin, Jan S, jeremiedbb, Joel Nothman, Joris Van den Bossche,
josephsalmon, Katrin Leinweber, Loic Esteve, Muhammad Hassaan Rafique, Nicolas
Hug, Olivier Grisel, Paul Paczuski, Reshama Shaikh, Sam Waterbury, Shivam
Kotwalia, Thomas Fan
.. _changes_0_20_1:
Version 0.20.1
==============
**November 21, 2018**
This is a bug-fix release with some minor documentation improvements and
enhancements to features released in 0.20.0. Note that we also include some
API changes in this release, so you might get some extra warnings after
updating from 0.20.0 to 0.20.1.
Changed models
--------------
The following estimators and functions, when fit with the same data and
parameters, may produce different models from the previous version. This often
occurs due to changes in the modelling logic (bug fixes or enhancements), or in
random sampling procedures.
- :class:`decomposition.IncrementalPCA` (bug fix)
Changelog
---------
:mod:`sklearn.cluster`
......................
- |Efficiency| make :class:`cluster.MeanShift` no longer try to do nested
parallelism as the overhead would hurt performance significantly when
``n_jobs > 1``.
:issue:`12159` by :user:`Olivier Grisel <ogrisel>`.
- |Fix| Fixed a bug in :class:`cluster.DBSCAN` with precomputed sparse neighbors
graph, which would add explicitly zeros on the diagonal even when already
present. :issue:`12105` by `Tom Dupre la Tour`_.
:mod:`sklearn.compose`
......................
- |Fix| Fixed an issue in :class:`compose.ColumnTransformer` when stacking
columns with types not convertible to a numeric.
:issue:`11912` by :user:`Adrin Jalali <adrinjalali>`.
- |API| :class:`compose.ColumnTransformer` now applies the ``sparse_threshold``
even if all transformation results are sparse. :issue:`12304` by `Andreas
Müller`_.
- |API| :func:`compose.make_column_transformer` now expects
``(transformer, columns)`` instead of ``(columns, transformer)`` to keep
consistent with :class:`compose.ColumnTransformer`.
:issue:`12339` by :user:`Adrin Jalali <adrinjalali>`.
:mod:`sklearn.datasets`
............................
- |Fix| :func:`datasets.fetch_openml` to correctly use the local cache.
:issue:`12246` by :user:`Jan N. van Rijn <janvanrijn>`.
- |Fix| :func:`datasets.fetch_openml` to correctly handle ignore attributes and
row id attributes. :issue:`12330` by :user:`Jan N. van Rijn <janvanrijn>`.
- |Fix| Fixed integer overflow in :func:`datasets.make_classification`
for values of ``n_informative`` parameter larger than 64.
:issue:`10811` by :user:`Roman Feldbauer <VarIr>`.
- |Fix| Fixed olivetti faces dataset ``DESCR`` attribute to point to the right
location in :func:`datasets.fetch_olivetti_faces`. :issue:`12441` by
:user:`Jérémie du Boisberranger <jeremiedbb>`
- |Fix| :func:`datasets.fetch_openml` to retry downloading when reading
from local cache fails. :issue:`12517` by :user:`Thomas Fan <thomasjpfan>`.
:mod:`sklearn.decomposition`
............................
- |Fix| Fixed a regression in :class:`decomposition.IncrementalPCA` where
0.20.0 raised an error if the number of samples in the final batch for
fitting IncrementalPCA was smaller than n_components.
:issue:`12234` by :user:`Ming Li <minggli>`.
:mod:`sklearn.ensemble`
.......................
- |Fix| Fixed a bug mostly affecting :class:`ensemble.RandomForestClassifier`
where ``class_weight='balanced_subsample'`` failed with more than 32 classes.
:issue:`12165` by `Joel Nothman`_.
- |Fix| Fixed a bug affecting :class:`ensemble.BaggingClassifier`,
:class:`ensemble.BaggingRegressor` and :class:`ensemble.IsolationForest`,
where ``max_features`` was sometimes rounded down to zero.
:issue:`12388` by :user:`Connor Tann <Connossor>`.
:mod:`sklearn.feature_extraction`
..................................
- |Fix| Fixed a regression in v0.20.0 where
:func:`feature_extraction.text.CountVectorizer` and other text vectorizers
could error during stop words validation with custom preprocessors
or tokenizers. :issue:`12393` by `Roman Yurchak`_.
:mod:`sklearn.linear_model`
...........................
- |Fix| :class:`linear_model.SGDClassifier` and variants
with ``early_stopping=True`` would not use a consistent validation
split in the multiclass case and this would cause a crash when using
those estimators as part of parallel parameter search or cross-validation.
:issue:`12122` by :user:`Olivier Grisel <ogrisel>`.
- |Fix| Fixed a bug affecting :class:`linear_model.SGDClassifier` in the multiclass
case. Each one-versus-all step is run in a :class:`joblib.Parallel` call and
mutating a common parameter, causing a segmentation fault if called within a
backend using processes and not threads. We now use ``require=sharedmem``
at the :class:`joblib.Parallel` instance creation. :issue:`12518` by
:user:`Pierre Glaser <pierreglaser>` and :user:`Olivier Grisel <ogrisel>`.
:mod:`sklearn.metrics`
......................
- |Fix| Fixed a bug in `metrics.pairwise.pairwise_distances_argmin_min`
which returned the square root of the distance when the metric parameter was
set to "euclidean". :issue:`12481` by
:user:`Jérémie du Boisberranger <jeremiedbb>`.
- |Fix| Fixed a bug in `metrics.pairwise.pairwise_distances_chunked`
which didn't ensure the diagonal is zero for euclidean distances.
:issue:`12612` by :user:`Andreas Müller <amueller>`.
- |API| The `metrics.calinski_harabaz_score` has been renamed to
:func:`metrics.calinski_harabasz_score` and will be removed in version 0.23.
:issue:`12211` by :user:`Lisa Thomas <LisaThomas9>`,
:user:`Mark Hannel <markhannel>` and :user:`Melissa Ferrari <mferrari3>`.
:mod:`sklearn.mixture`
........................
- |Fix| Ensure that the ``fit_predict`` method of
:class:`mixture.GaussianMixture` and :class:`mixture.BayesianGaussianMixture`
always yield assignments consistent with ``fit`` followed by ``predict`` even
if the convergence criterion is too loose or not met. :issue:`12451`
by :user:`Olivier Grisel <ogrisel>`.
:mod:`sklearn.neighbors`
........................
- |Fix| force the parallelism backend to :code:`threading` for
:class:`neighbors.KDTree` and :class:`neighbors.BallTree` in Python 2.7 to
avoid pickling errors caused by the serialization of their methods.
:issue:`12171` by :user:`Thomas Moreau <tomMoral>`.
:mod:`sklearn.preprocessing`
.............................
- |Fix| Fixed bug in :class:`preprocessing.OrdinalEncoder` when passing
manually specified categories. :issue:`12365` by `Joris Van den Bossche`_.
- |Fix| Fixed bug in :class:`preprocessing.KBinsDiscretizer` where the
``transform`` method mutates the ``_encoder`` attribute. The ``transform``
method is now thread safe. :issue:`12514` by
:user:`Hanmin Qin <qinhanmin2014>`.
- |Fix| Fixed a bug in :class:`preprocessing.PowerTransformer` where the
Yeo-Johnson transform was incorrect for lambda parameters outside of `[0, 2]`
:issue:`12522` by :user:`Nicolas Hug<NicolasHug>`.
- |Fix| Fixed a bug in :class:`preprocessing.OneHotEncoder` where transform
failed when set to ignore unknown numpy strings of different lengths
:issue:`12471` by :user:`Gabriel Marzinotto<GMarzinotto>`.
- |API| The default value of the :code:`method` argument in
:func:`preprocessing.power_transform` will be changed from :code:`box-cox`
to :code:`yeo-johnson` to match :class:`preprocessing.PowerTransformer`
in version 0.23. A FutureWarning is raised when the default value is used.
:issue:`12317` by :user:`Eric Chang <chang>`.
:mod:`sklearn.utils`
........................
- |Fix| Use float64 for mean accumulator to avoid floating point
precision issues in :class:`preprocessing.StandardScaler` and
:class:`decomposition.IncrementalPCA` when using float32 datasets.
:issue:`12338` by :user:`bauks <bauks>`.
- |Fix| Calling :func:`utils.check_array` on `pandas.Series`, which
raised an error in 0.20.0, now returns the expected output again.
:issue:`12625` by `Andreas Müller`_
Miscellaneous
.............
- |Fix| When using site joblib by setting the environment variable
`SKLEARN_SITE_JOBLIB`, added compatibility with joblib 0.11 in addition
to 0.12+. :issue:`12350` by `Joel Nothman`_ and `Roman Yurchak`_.
- |Fix| Make sure to avoid raising ``FutureWarning`` when calling
``np.vstack`` with numpy 1.16 and later (use list comprehensions
instead of generator expressions in many locations of the scikit-learn
code base). :issue:`12467` by :user:`Olivier Grisel <ogrisel>`.
- |API| Removed all mentions of ``sklearn.externals.joblib``, and deprecated
joblib methods exposed in ``sklearn.utils``, except for
:func:`utils.parallel_backend` and :func:`utils.register_parallel_backend`,
which allow users to configure parallel computation in scikit-learn.
Other functionalities are part of `joblib <https://joblib.readthedocs.io/>`_.
package and should be used directly, by installing it.
The goal of this change is to prepare for
unvendoring joblib in future version of scikit-learn.
:issue:`12345` by :user:`Thomas Moreau <tomMoral>`
Code and Documentation Contributors
-----------------------------------
With thanks to:
^__^, Adrin Jalali, Andrea Navarrete, Andreas Mueller,
bauks, BenjaStudio, Cheuk Ting Ho, Connossor,
Corey Levinson, Dan Stine, daten-kieker, Denis Kataev,
Dillon Gardner, Dmitry Vukolov, Dougal J. Sutherland, Edward J Brown,
Eric Chang, Federico Caselli, Gabriel Marzinotto, Gael Varoquaux,
GauravAhlawat, Gustavo De Mari Pereira, Hanmin Qin, haroldfox,
JackLangerman, Jacopo Notarstefano, janvanrijn, jdethurens,
jeremiedbb, Joel Nothman, Joris Van den Bossche, Koen,
Kushal Chauhan, Lee Yi Jie Joel, Lily Xiong, mail-liam,
Mark Hannel, melsyt, Ming Li, Nicholas Smith,
Nicolas Hug, Nikolay Shebanov, Oleksandr Pavlyk, Olivier Grisel,
Peter Hausamann, Pierre Glaser, Pulkit Maloo, Quentin Batista,
Radostin Stoyanov, Ramil Nugmanov, Rebekah Kim, Reshama Shaikh,
Rohan Singh, Roman Feldbauer, Roman Yurchak, Roopam Sharma,
Sam Waterbury, Scott Lowe, Sebastian Raschka, Stephen Tierney,
SylvainLan, TakingItCasual, Thomas Fan, Thomas Moreau,
Tom Dupré la Tour, Tulio Casagrande, Utkarsh Upadhyay, Xing Han Lu,
Yaroslav Halchenko, Zach Miller
.. _changes_0_20:
Version 0.20.0
==============
**September 25, 2018**
This release packs in a mountain of bug fixes, features and enhancements for
the Scikit-learn library, and improvements to the documentation and examples.
Thanks to our contributors!
This release is dedicated to the memory of Raghav Rajagopalan.
Highlights
----------
We have tried to improve our support for common data-science use-cases
including missing values, categorical variables, heterogeneous data, and
features/targets with unusual distributions.
Missing values in features, represented by NaNs, are now accepted in
column-wise preprocessing such as scalers. Each feature is fitted disregarding
NaNs, and data containing NaNs can be transformed. The new :mod:`sklearn.impute`
module provides estimators for learning despite missing data.
:class:`~compose.ColumnTransformer` handles the case where different features
or columns of a pandas.DataFrame need different preprocessing.
String or pandas Categorical columns can now be encoded with
:class:`~preprocessing.OneHotEncoder` or
:class:`~preprocessing.OrdinalEncoder`.
:class:`~compose.TransformedTargetRegressor` helps when the regression target
needs to be transformed to be modeled. :class:`~preprocessing.PowerTransformer`
and :class:`~preprocessing.KBinsDiscretizer` join
:class:`~preprocessing.QuantileTransformer` as non-linear transformations.
Beyond this, we have added :term:`sample_weight` support to several estimators
(including :class:`~cluster.KMeans`, :class:`~linear_model.BayesianRidge` and
:class:`~neighbors.KernelDensity`) and improved stopping criteria in others
(including :class:`~neural_network.MLPRegressor`,
:class:`~ensemble.GradientBoostingRegressor` and
:class:`~linear_model.SGDRegressor`).
This release is also the first to be accompanied by a :ref:`glossary` developed
by `Joel Nothman`_. The glossary is a reference resource to help users and
contributors become familiar with the terminology and conventions used in
Scikit-learn.
Sorry if your contribution didn't make it into the highlights. There's a lot
here...
Changed models
--------------
The following estimators and functions, when fit with the same data and
parameters, may produce different models from the previous version. This often
occurs due to changes in the modelling logic (bug fixes or enhancements), or in
random sampling procedures.
- :class:`cluster.MeanShift` (bug fix)
- :class:`decomposition.IncrementalPCA` in Python 2 (bug fix)
- :class:`decomposition.SparsePCA` (bug fix)
- :class:`ensemble.GradientBoostingClassifier` (bug fix affecting feature importances)
- :class:`isotonic.IsotonicRegression` (bug fix)
- :class:`linear_model.ARDRegression` (bug fix)
- :class:`linear_model.LogisticRegressionCV` (bug fix)
- :class:`linear_model.OrthogonalMatchingPursuit` (bug fix)
- :class:`linear_model.PassiveAggressiveClassifier` (bug fix)
- :class:`linear_model.PassiveAggressiveRegressor` (bug fix)
- :class:`linear_model.Perceptron` (bug fix)
- :class:`linear_model.SGDClassifier` (bug fix)
- :class:`linear_model.SGDRegressor` (bug fix)
- :class:`metrics.roc_auc_score` (bug fix)
- :class:`metrics.roc_curve` (bug fix)
- `neural_network.BaseMultilayerPerceptron` (bug fix)
- :class:`neural_network.MLPClassifier` (bug fix)
- :class:`neural_network.MLPRegressor` (bug fix)
- The v0.19.0 release notes failed to mention a backwards incompatibility with
:class:`model_selection.StratifiedKFold` when ``shuffle=True`` due to
:issue:`7823`.
Details are listed in the changelog below.
(While we are trying to better inform users by providing this information, we
cannot assure that this list is complete.)
Known Major Bugs
----------------
* :issue:`11924`: :class:`linear_model.LogisticRegressionCV` with
`solver='lbfgs'` and `multi_class='multinomial'` may be non-deterministic or
otherwise broken on macOS. This appears to be the case on Travis CI servers,
but has not been confirmed on personal MacBooks! This issue has been present
in previous releases.
* :issue:`9354`: :func:`metrics.pairwise.euclidean_distances` (which is used
several times throughout the library) gives results with poor precision,
which particularly affects its use with 32-bit float inputs. This became
more problematic in versions 0.18 and 0.19 when some algorithms were changed
to avoid casting 32-bit data into 64-bit.
Changelog
---------
Support for Python 3.3 has been officially dropped.
:mod:`sklearn.cluster`
......................
- |MajorFeature| :class:`cluster.AgglomerativeClustering` now supports Single
Linkage clustering via ``linkage='single'``. :issue:`9372` by :user:`Leland
McInnes <lmcinnes>` and :user:`Steve Astels <sastels>`.
- |Feature| :class:`cluster.KMeans` and :class:`cluster.MiniBatchKMeans` now support
sample weights via new parameter ``sample_weight`` in ``fit`` function.
:issue:`10933` by :user:`Johannes Hansen <jnhansen>`.
- |Efficiency| :class:`cluster.KMeans`, :class:`cluster.MiniBatchKMeans` and
:func:`cluster.k_means` passed with ``algorithm='full'`` now enforces
row-major ordering, improving runtime.
:issue:`10471` by :user:`Gaurav Dhingra <gxyd>`.
- |Efficiency| :class:`cluster.DBSCAN` now is parallelized according to ``n_jobs``
regardless of ``algorithm``.
:issue:`8003` by :user:`Joël Billaud <recamshak>`.
- |Enhancement| :class:`cluster.KMeans` now gives a warning if the number of
distinct clusters found is smaller than ``n_clusters``. This may occur when
the number of distinct points in the data set is actually smaller than the
number of cluster one is looking for.
:issue:`10059` by :user:`Christian Braune <christianbraune79>`.
- |Fix| Fixed a bug where the ``fit`` method of
:class:`cluster.AffinityPropagation` stored cluster
centers as 3d array instead of 2d array in case of non-convergence. For the
same class, fixed undefined and arbitrary behavior in case of training data
where all samples had equal similarity.
:issue:`9612`. By :user:`Jonatan Samoocha <jsamoocha>`.
- |Fix| Fixed a bug in :func:`cluster.spectral_clustering` where the normalization of
the spectrum was using a division instead of a multiplication. :issue:`8129`
by :user:`Jan Margeta <jmargeta>`, :user:`Guillaume Lemaitre <glemaitre>`,
and :user:`Devansh D. <devanshdalal>`.
- |Fix| Fixed a bug in `cluster.k_means_elkan` where the returned
``iteration`` was 1 less than the correct value. Also added the missing
``n_iter_`` attribute in the docstring of :class:`cluster.KMeans`.
:issue:`11353` by :user:`Jeremie du Boisberranger <jeremiedbb>`.
- |Fix| Fixed a bug in :func:`cluster.mean_shift` where the assigned labels
were not deterministic if there were multiple clusters with the same
intensities.
:issue:`11901` by :user:`Adrin Jalali <adrinjalali>`.
- |API| Deprecate ``pooling_func`` unused parameter in
:class:`cluster.AgglomerativeClustering`.
:issue:`9875` by :user:`Kumar Ashutosh <thechargedneutron>`.
:mod:`sklearn.compose`
......................
- New module.
- |MajorFeature| Added :class:`compose.ColumnTransformer`, which allows to
apply different transformers to different columns of arrays or pandas
DataFrames. :issue:`9012` by `Andreas Müller`_ and `Joris Van den Bossche`_,
and :issue:`11315` by :user:`Thomas Fan <thomasjpfan>`.
- |MajorFeature| Added the :class:`compose.TransformedTargetRegressor` which
transforms the target y before fitting a regression model. The predictions
are mapped back to the original space via an inverse transform. :issue:`9041`
by `Andreas Müller`_ and :user:`Guillaume Lemaitre <glemaitre>`.
:mod:`sklearn.covariance`
.........................
- |Efficiency| Runtime improvements to :class:`covariance.GraphicalLasso`.
:issue:`9858` by :user:`Steven Brown <stevendbrown>`.
- |API| The `covariance.graph_lasso`,
`covariance.GraphLasso` and `covariance.GraphLassoCV` have been
renamed to :func:`covariance.graphical_lasso`,
:class:`covariance.GraphicalLasso` and :class:`covariance.GraphicalLassoCV`
respectively and will be removed in version 0.22.
:issue:`9993` by :user:`Artiem Krinitsyn <artiemq>`
:mod:`sklearn.datasets`
.......................
- |MajorFeature| Added :func:`datasets.fetch_openml` to fetch datasets from
`OpenML <https://openml.org>`_. OpenML is a free, open data sharing platform
and will be used instead of mldata as it provides better service availability.
:issue:`9908` by `Andreas Müller`_ and :user:`Jan N. van Rijn <janvanrijn>`.
- |Feature| In :func:`datasets.make_blobs`, one can now pass a list to the
``n_samples`` parameter to indicate the number of samples to generate per
cluster. :issue:`8617` by :user:`Maskani Filali Mohamed <maskani-moh>` and
:user:`Konstantinos Katrioplas <kkatrio>`.
- |Feature| Add ``filename`` attribute to :mod:`sklearn.datasets` that have a CSV file.
:issue:`9101` by :user:`alex-33 <alex-33>`
and :user:`Maskani Filali Mohamed <maskani-moh>`.
- |Feature| ``return_X_y`` parameter has been added to several dataset loaders.
:issue:`10774` by :user:`Chris Catalfo <ccatalfo>`.
- |Fix| Fixed a bug in `datasets.load_boston` which had a wrong data
point. :issue:`10795` by :user:`Takeshi Yoshizawa <tarcusx>`.
- |Fix| Fixed a bug in :func:`datasets.load_iris` which had two wrong data points.
:issue:`11082` by :user:`Sadhana Srinivasan <rotuna>`
and :user:`Hanmin Qin <qinhanmin2014>`.
- |Fix| Fixed a bug in :func:`datasets.fetch_kddcup99`, where data were not
properly shuffled. :issue:`9731` by `Nicolas Goix`_.
- |Fix| Fixed a bug in :func:`datasets.make_circles`, where no odd number of
data points could be generated. :issue:`10045` by :user:`Christian Braune
<christianbraune79>`.
- |API| Deprecated `sklearn.datasets.fetch_mldata` to be removed in
version 0.22. mldata.org is no longer operational. Until removal it will
remain possible to load cached datasets. :issue:`11466` by `Joel Nothman`_.
:mod:`sklearn.decomposition`
............................
- |Feature| :func:`decomposition.dict_learning` functions and models now
support positivity constraints. This applies to the dictionary and sparse
code. :issue:`6374` by :user:`John Kirkham <jakirkham>`.
- |Feature| |Fix| :class:`decomposition.SparsePCA` now exposes
``normalize_components``. When set to True, the train and test data are
centered with the train mean respectively during the fit phase and the
transform phase. This fixes the behavior of SparsePCA. When set to False,
which is the default, the previous abnormal behaviour still holds. The False
value is for backward compatibility and should not be used. :issue:`11585`
by :user:`Ivan Panico <FollowKenny>`.
- |Efficiency| Efficiency improvements in :func:`decomposition.dict_learning`.
:issue:`11420` and others by :user:`John Kirkham <jakirkham>`.
- |Fix| Fix for uninformative error in :class:`decomposition.IncrementalPCA`:
now an error is raised if the number of components is larger than the
chosen batch size. The ``n_components=None`` case was adapted accordingly.
:issue:`6452`. By :user:`Wally Gauze <wallygauze>`.
- |Fix| Fixed a bug where the ``partial_fit`` method of
:class:`decomposition.IncrementalPCA` used integer division instead of float
division on Python 2.
:issue:`9492` by :user:`James Bourbeau <jrbourbeau>`.
- |Fix| In :class:`decomposition.PCA` selecting a n_components parameter greater
than the number of samples now raises an error. Similarly, the
``n_components=None`` case now selects the minimum of ``n_samples`` and
``n_features``.
:issue:`8484` by :user:`Wally Gauze <wallygauze>`.
- |Fix| Fixed a bug in :class:`decomposition.PCA` where users will get
unexpected error with large datasets when ``n_components='mle'`` on Python 3
versions.
:issue:`9886` by :user:`Hanmin Qin <qinhanmin2014>`.
- |Fix| Fixed an underflow in calculating KL-divergence for
:class:`decomposition.NMF` :issue:`10142` by `Tom Dupre la Tour`_.
- |Fix| Fixed a bug in :class:`decomposition.SparseCoder` when running OMP
sparse coding in parallel using read-only memory mapped datastructures.
:issue:`5956` by :user:`Vighnesh Birodkar <vighneshbirodkar>` and
:user:`Olivier Grisel <ogrisel>`.
:mod:`sklearn.discriminant_analysis`
....................................
- |Efficiency| Memory usage improvement for `_class_means` and
`_class_cov` in :mod:`sklearn.discriminant_analysis`. :issue:`10898` by
:user:`Nanxin Chen <bobchennan>`.
:mod:`sklearn.dummy`
....................
- |Feature| :class:`dummy.DummyRegressor` now has a ``return_std`` option in its
``predict`` method. The returned standard deviations will be zeros.
- |Feature| :class:`dummy.DummyClassifier` and :class:`dummy.DummyRegressor` now
only require X to be an object with finite length or shape. :issue:`9832` by
:user:`Vrishank Bhardwaj <vrishank97>`.
- |Feature| :class:`dummy.DummyClassifier` and :class:`dummy.DummyRegressor`
can now be scored without supplying test samples.
:issue:`11951` by :user:`Rüdiger Busche <JarnoRFB>`.
:mod:`sklearn.ensemble`
.......................
- |Feature| :class:`ensemble.BaggingRegressor` and
:class:`ensemble.BaggingClassifier` can now be fit with missing/non-finite
values in X and/or multi-output Y to support wrapping pipelines that perform
their own imputation. :issue:`9707` by :user:`Jimmy Wan <jimmywan>`.
- |Feature| :class:`ensemble.GradientBoostingClassifier` and
:class:`ensemble.GradientBoostingRegressor` now support early stopping
via ``n_iter_no_change``, ``validation_fraction`` and ``tol``. :issue:`7071`
by `Raghav RV`_
- |Feature| Added ``named_estimators_`` parameter in
:class:`ensemble.VotingClassifier` to access fitted estimators.
:issue:`9157` by :user:`Herilalaina Rakotoarison <herilalaina>`.
- |Fix| Fixed a bug when fitting :class:`ensemble.GradientBoostingClassifier` or
:class:`ensemble.GradientBoostingRegressor` with ``warm_start=True`` which
previously raised a segmentation fault due to a non-conversion of CSC matrix
into CSR format expected by ``decision_function``. Similarly, Fortran-ordered
arrays are converted to C-ordered arrays in the dense case. :issue:`9991` by
:user:`Guillaume Lemaitre <glemaitre>`.
- |Fix| Fixed a bug in :class:`ensemble.GradientBoostingRegressor`
and :class:`ensemble.GradientBoostingClassifier` to have
feature importances summed and then normalized, rather than normalizing on a
per-tree basis. The previous behavior over-weighted the Gini importance of
features that appear in later stages. This issue only affected feature
importances. :issue:`11176` by :user:`Gil Forsyth <gforsyth>`.
- |API| The default value of the ``n_estimators`` parameter of
:class:`ensemble.RandomForestClassifier`, :class:`ensemble.RandomForestRegressor`,
:class:`ensemble.ExtraTreesClassifier`, :class:`ensemble.ExtraTreesRegressor`,
and :class:`ensemble.RandomTreesEmbedding` will change from 10 in version 0.20
to 100 in 0.22. A FutureWarning is raised when the default value is used.
:issue:`11542` by :user:`Anna Ayzenshtat <annaayzenshtat>`.
- |API| Classes derived from `ensemble.BaseBagging`. The attribute
``estimators_samples_`` will return a list of arrays containing the indices
selected for each bootstrap instead of a list of arrays containing the mask
of the samples selected for each bootstrap. Indices allows to repeat samples
while mask does not allow this functionality.
:issue:`9524` by :user:`Guillaume Lemaitre <glemaitre>`.
- |Fix| `ensemble.BaseBagging` where one could not deterministically
reproduce ``fit`` result using the object attributes when ``random_state``
is set. :issue:`9723` by :user:`Guillaume Lemaitre <glemaitre>`.
:mod:`sklearn.feature_extraction`
.................................
- |Feature| Enable the call to `get_feature_names` in unfitted
:class:`feature_extraction.text.CountVectorizer` initialized with a
vocabulary. :issue:`10908` by :user:`Mohamed Maskani <maskani-moh>`.
- |Enhancement| ``idf_`` can now be set on a
:class:`feature_extraction.text.TfidfTransformer`.
:issue:`10899` by :user:`Sergey Melderis <serega>`.
- |Fix| Fixed a bug in :func:`feature_extraction.image.extract_patches_2d` which
would throw an exception if ``max_patches`` was greater than or equal to the
number of all possible patches rather than simply returning the number of
possible patches. :issue:`10101` by :user:`Varun Agrawal <varunagrawal>`
- |Fix| Fixed a bug in :class:`feature_extraction.text.CountVectorizer`,
:class:`feature_extraction.text.TfidfVectorizer`,
:class:`feature_extraction.text.HashingVectorizer` to support 64 bit sparse
array indexing necessary to process large datasets with more than 2·10⁹ tokens
(words or n-grams). :issue:`9147` by :user:`Claes-Fredrik Mannby <mannby>`
and `Roman Yurchak`_.
- |Fix| Fixed bug in :class:`feature_extraction.text.TfidfVectorizer` which
was ignoring the parameter ``dtype``. In addition,
:class:`feature_extraction.text.TfidfTransformer` will preserve ``dtype``
for floating and raise a warning if ``dtype`` requested is integer.
:issue:`10441` by :user:`Mayur Kulkarni <maykulkarni>` and
:user:`Guillaume Lemaitre <glemaitre>`.
:mod:`sklearn.feature_selection`
................................
- |Feature| Added select K best features functionality to
:class:`feature_selection.SelectFromModel`.
:issue:`6689` by :user:`Nihar Sheth <nsheth12>` and
:user:`Quazi Rahman <qmaruf>`.
- |Feature| Added ``min_features_to_select`` parameter to
:class:`feature_selection.RFECV` to bound evaluated features counts.
:issue:`11293` by :user:`Brent Yi <brentyi>`.
- |Feature| :class:`feature_selection.RFECV`'s fit method now supports
:term:`groups`. :issue:`9656` by :user:`Adam Greenhall <adamgreenhall>`.
- |Fix| Fixed computation of ``n_features_to_compute`` for edge case with tied
CV scores in :class:`feature_selection.RFECV`.
:issue:`9222` by :user:`Nick Hoh <nickypie>`.
:mod:`sklearn.gaussian_process`
...............................
- |Efficiency| In :class:`gaussian_process.GaussianProcessRegressor`, method
``predict`` is faster when using ``return_std=True`` in particular more when
called several times in a row. :issue:`9234` by :user:`andrewww <andrewww>`
and :user:`Minghui Liu <minghui-liu>`.
:mod:`sklearn.impute`
.....................
- New module, adopting ``preprocessing.Imputer`` as
:class:`impute.SimpleImputer` with minor changes (see under preprocessing
below).
- |MajorFeature| Added :class:`impute.MissingIndicator` which generates a
binary indicator for missing values. :issue:`8075` by :user:`Maniteja Nandana
<maniteja123>` and :user:`Guillaume Lemaitre <glemaitre>`.
- |Feature| The :class:`impute.SimpleImputer` has a new strategy,
``'constant'``, to complete missing values with a fixed one, given by the
``fill_value`` parameter. This strategy supports numeric and non-numeric
data, and so does the ``'most_frequent'`` strategy now. :issue:`11211` by
:user:`Jeremie du Boisberranger <jeremiedbb>`.
:mod:`sklearn.isotonic`
.......................
- |Fix| Fixed a bug in :class:`isotonic.IsotonicRegression` which incorrectly
combined weights when fitting a model to data involving points with
identical X values.
:issue:`9484` by :user:`Dallas Card <dallascard>`
:mod:`sklearn.linear_model`
...........................
- |Feature| :class:`linear_model.SGDClassifier`,
:class:`linear_model.SGDRegressor`,
:class:`linear_model.PassiveAggressiveClassifier`,
:class:`linear_model.PassiveAggressiveRegressor` and
:class:`linear_model.Perceptron` now expose ``early_stopping``,
``validation_fraction`` and ``n_iter_no_change`` parameters, to stop
optimization monitoring the score on a validation set. A new learning rate
``"adaptive"`` strategy divides the learning rate by 5 each time
``n_iter_no_change`` consecutive epochs fail to improve the model.
:issue:`9043` by `Tom Dupre la Tour`_.
- |Feature| Add `sample_weight` parameter to the fit method of
:class:`linear_model.BayesianRidge` for weighted linear regression.
:issue:`10112` by :user:`Peter St. John <pstjohn>`.
- |Fix| Fixed a bug in `logistic.logistic_regression_path` to ensure
that the returned coefficients are correct when ``multiclass='multinomial'``.
Previously, some of the coefficients would override each other, leading to
incorrect results in :class:`linear_model.LogisticRegressionCV`.
:issue:`11724` by :user:`Nicolas Hug <NicolasHug>`.
- |Fix| Fixed a bug in :class:`linear_model.LogisticRegression` where when using
the parameter ``multi_class='multinomial'``, the ``predict_proba`` method was
returning incorrect probabilities in the case of binary outcomes.
:issue:`9939` by :user:`Roger Westover <rwolst>`.
- |Fix| Fixed a bug in :class:`linear_model.LogisticRegressionCV` where the
``score`` method always computes accuracy, not the metric given by
the ``scoring`` parameter.
:issue:`10998` by :user:`Thomas Fan <thomasjpfan>`.
- |Fix| Fixed a bug in :class:`linear_model.LogisticRegressionCV` where the
'ovr' strategy was always used to compute cross-validation scores in the
multiclass setting, even if ``'multinomial'`` was set.
:issue:`8720` by :user:`William de Vazelhes <wdevazelhes>`.
- |Fix| Fixed a bug in :class:`linear_model.OrthogonalMatchingPursuit` that was
broken when setting ``normalize=False``.
:issue:`10071` by `Alexandre Gramfort`_.
- |Fix| Fixed a bug in :class:`linear_model.ARDRegression` which caused
incorrectly updated estimates for the standard deviation and the
coefficients. :issue:`10153` by :user:`Jörg Döpfert <jdoepfert>`.
- |Fix| Fixed a bug in :class:`linear_model.ARDRegression` and
:class:`linear_model.BayesianRidge` which caused NaN predictions when fitted
with a constant target.
:issue:`10095` by :user:`Jörg Döpfert <jdoepfert>`.
- |Fix| Fixed a bug in :class:`linear_model.RidgeClassifierCV` where
the parameter ``store_cv_values`` was not implemented though
it was documented in ``cv_values`` as a way to set up the storage
of cross-validation values for different alphas. :issue:`10297` by
:user:`Mabel Villalba-Jiménez <mabelvj>`.
- |Fix| Fixed a bug in :class:`linear_model.ElasticNet` which caused the input
to be overridden when using parameter ``copy_X=True`` and
``check_input=False``. :issue:`10581` by :user:`Yacine Mazari <ymazari>`.
- |Fix| Fixed a bug in :class:`sklearn.linear_model.Lasso`
where the coefficient had wrong shape when ``fit_intercept=False``.
:issue:`10687` by :user:`Martin Hahn <martin-hahn>`.
- |Fix| Fixed a bug in :func:`sklearn.linear_model.LogisticRegression` where the
``multi_class='multinomial'`` with binary output ``with warm_start=True``
:issue:`10836` by :user:`Aishwarya Srinivasan <aishgrt1>`.
- |Fix| Fixed a bug in :class:`linear_model.RidgeCV` where using integer
``alphas`` raised an error.
:issue:`10397` by :user:`Mabel Villalba-Jiménez <mabelvj>`.
- |Fix| Fixed condition triggering gap computation in
:class:`linear_model.Lasso` and :class:`linear_model.ElasticNet` when working
with sparse matrices. :issue:`10992` by `Alexandre Gramfort`_.
- |Fix| Fixed a bug in :class:`linear_model.SGDClassifier`,
:class:`linear_model.SGDRegressor`,
:class:`linear_model.PassiveAggressiveClassifier`,
:class:`linear_model.PassiveAggressiveRegressor` and
:class:`linear_model.Perceptron`, where the stopping criterion was stopping
the algorithm before convergence. A parameter ``n_iter_no_change`` was added
and set by default to 5. Previous behavior is equivalent to setting the
parameter to 1. :issue:`9043` by `Tom Dupre la Tour`_.
- |Fix| Fixed a bug where liblinear and libsvm-based estimators would segfault
if passed a scipy.sparse matrix with 64-bit indices. They now raise a
ValueError.
:issue:`11327` by :user:`Karan Dhingra <kdhingra307>` and `Joel Nothman`_.
- |API| The default values of the ``solver`` and ``multi_class`` parameters of
:class:`linear_model.LogisticRegression` will change respectively from
``'liblinear'`` and ``'ovr'`` in version 0.20 to ``'lbfgs'`` and
``'auto'`` in version 0.22. A FutureWarning is raised when the default
values are used. :issue:`11905` by `Tom Dupre la Tour`_ and `Joel Nothman`_.
- |API| Deprecate ``positive=True`` option in :class:`linear_model.Lars` as
the underlying implementation is broken. Use :class:`linear_model.Lasso`
instead. :issue:`9837` by `Alexandre Gramfort`_.
- |API| ``n_iter_`` may vary from previous releases in
:class:`linear_model.LogisticRegression` with ``solver='lbfgs'`` and
:class:`linear_model.HuberRegressor`. For Scipy <= 1.0.0, the optimizer could
perform more than the requested maximum number of iterations. Now both
estimators will report at most ``max_iter`` iterations even if more were
performed. :issue:`10723` by `Joel Nothman`_.
:mod:`sklearn.manifold`
.......................
- |Efficiency| Speed improvements for both 'exact' and 'barnes_hut' methods in
:class:`manifold.TSNE`. :issue:`10593` and :issue:`10610` by
`Tom Dupre la Tour`_.
- |Feature| Support sparse input in :meth:`manifold.Isomap.fit`.
:issue:`8554` by :user:`Leland McInnes <lmcinnes>`.
- |Feature| `manifold.t_sne.trustworthiness` accepts metrics other than
Euclidean. :issue:`9775` by :user:`William de Vazelhes <wdevazelhes>`.
- |Fix| Fixed a bug in :func:`manifold.spectral_embedding` where the
normalization of the spectrum was using a division instead of a
multiplication. :issue:`8129` by :user:`Jan Margeta <jmargeta>`,
:user:`Guillaume Lemaitre <glemaitre>`, and :user:`Devansh D.
<devanshdalal>`.
- |API| |Feature| Deprecate ``precomputed`` parameter in function
`manifold.t_sne.trustworthiness`. Instead, the new parameter ``metric``
should be used with any compatible metric including 'precomputed', in which
case the input matrix ``X`` should be a matrix of pairwise distances or
squared distances. :issue:`9775` by :user:`William de Vazelhes
<wdevazelhes>`.
- |API| Deprecate ``precomputed`` parameter in function
`manifold.t_sne.trustworthiness`. Instead, the new parameter
``metric`` should be used with any compatible metric including
'precomputed', in which case the input matrix ``X`` should be a matrix of
pairwise distances or squared distances. :issue:`9775` by
:user:`William de Vazelhes <wdevazelhes>`.
:mod:`sklearn.metrics`
......................
- |MajorFeature| Added the :func:`metrics.davies_bouldin_score` metric for
evaluation of clustering models without a ground truth. :issue:`10827` by
:user:`Luis Osa <logc>`.
- |MajorFeature| Added the :func:`metrics.balanced_accuracy_score` metric and
a corresponding ``'balanced_accuracy'`` scorer for binary and multiclass
classification. :issue:`8066` by :user:`xyguo` and :user:`Aman Dalmia
<dalmia>`, and :issue:`10587` by `Joel Nothman`_.
- |Feature| Partial AUC is available via ``max_fpr`` parameter in
:func:`metrics.roc_auc_score`. :issue:`3840` by
:user:`Alexander Niederbühl <Alexander-N>`.
- |Feature| A scorer based on :func:`metrics.brier_score_loss` is also
available. :issue:`9521` by :user:`Hanmin Qin <qinhanmin2014>`.
- |Feature| Added control over the normalization in
:func:`metrics.normalized_mutual_info_score` and
:func:`metrics.adjusted_mutual_info_score` via the ``average_method``
parameter. In version 0.22, the default normalizer for each will become
the *arithmetic* mean of the entropies of each clustering. :issue:`11124` by
:user:`Arya McCarthy <aryamccarthy>`.
- |Feature| Added ``output_dict`` parameter in :func:`metrics.classification_report`
to return classification statistics as dictionary.
:issue:`11160` by :user:`Dan Barkhorn <danielbarkhorn>`.
- |Feature| :func:`metrics.classification_report` now reports all applicable averages on
the given data, including micro, macro and weighted average as well as samples
average for multilabel data. :issue:`11679` by :user:`Alexander Pacha <apacha>`.
- |Feature| :func:`metrics.average_precision_score` now supports binary
``y_true`` other than ``{0, 1}`` or ``{-1, 1}`` through ``pos_label``
parameter. :issue:`9980` by :user:`Hanmin Qin <qinhanmin2014>`.
- |Feature| :func:`metrics.label_ranking_average_precision_score` now supports
``sample_weight``.
:issue:`10845` by :user:`Jose Perez-Parras Toledano <jopepato>`.
- |Feature| Add ``dense_output`` parameter to :func:`metrics.pairwise.linear_kernel`.
When False and both inputs are sparse, will return a sparse matrix.
:issue:`10999` by :user:`Taylor G Smith <tgsmith61591>`.
- |Efficiency| :func:`metrics.silhouette_score` and
:func:`metrics.silhouette_samples` are more memory efficient and run
faster. This avoids some reported freezes and MemoryErrors.
:issue:`11135` by `Joel Nothman`_.
- |Fix| Fixed a bug in :func:`metrics.precision_recall_fscore_support`
when truncated `range(n_labels)` is passed as value for `labels`.
:issue:`10377` by :user:`Gaurav Dhingra <gxyd>`.
- |Fix| Fixed a bug due to floating point error in
:func:`metrics.roc_auc_score` with non-integer sample weights. :issue:`9786`
by :user:`Hanmin Qin <qinhanmin2014>`.
- |Fix| Fixed a bug where :func:`metrics.roc_curve` sometimes starts on y-axis
instead of (0, 0), which is inconsistent with the document and other
implementations. Note that this will not influence the result from
:func:`metrics.roc_auc_score` :issue:`10093` by :user:`alexryndin
<alexryndin>` and :user:`Hanmin Qin <qinhanmin2014>`.
- |Fix| Fixed a bug to avoid integer overflow. Casted product to 64 bits integer in
:func:`metrics.mutual_info_score`.
:issue:`9772` by :user:`Kumar Ashutosh <thechargedneutron>`.
- |Fix| Fixed a bug where :func:`metrics.average_precision_score` will sometimes return
``nan`` when ``sample_weight`` contains 0.
:issue:`9980` by :user:`Hanmin Qin <qinhanmin2014>`.
- |Fix| Fixed a bug in :func:`metrics.fowlkes_mallows_score` to avoid integer
overflow. Casted return value of `contingency_matrix` to `int64` and computed
product of square roots rather than square root of product.
:issue:`9515` by :user:`Alan Liddell <aliddell>` and
:user:`Manh Dao <manhdao>`.
- |API| Deprecate ``reorder`` parameter in :func:`metrics.auc` as it's no
longer required for :func:`metrics.roc_auc_score`. Moreover using
``reorder=True`` can hide bugs due to floating point error in the input.
:issue:`9851` by :user:`Hanmin Qin <qinhanmin2014>`.
- |API| In :func:`metrics.normalized_mutual_info_score` and
:func:`metrics.adjusted_mutual_info_score`, warn that
``average_method`` will have a new default value. In version 0.22, the
default normalizer for each will become the *arithmetic* mean of the
entropies of each clustering. Currently,
:func:`metrics.normalized_mutual_info_score` uses the default of
``average_method='geometric'``, and
:func:`metrics.adjusted_mutual_info_score` uses the default of
``average_method='max'`` to match their behaviors in version 0.19.
:issue:`11124` by :user:`Arya McCarthy <aryamccarthy>`.
- |API| The ``batch_size`` parameter to :func:`metrics.pairwise_distances_argmin_min`
and :func:`metrics.pairwise_distances_argmin` is deprecated to be removed in
v0.22. It no longer has any effect, as batch size is determined by global
``working_memory`` config. See :ref:`working_memory`. :issue:`10280` by `Joel
Nothman`_ and :user:`Aman Dalmia <dalmia>`.
:mod:`sklearn.mixture`
......................
- |Feature| Added function :term:`fit_predict` to :class:`mixture.GaussianMixture`
and :class:`mixture.GaussianMixture`, which is essentially equivalent to
calling :term:`fit` and :term:`predict`. :issue:`10336` by :user:`Shu Haoran
<haoranShu>` and :user:`Andrew Peng <Andrew-peng>`.
- |Fix| Fixed a bug in `mixture.BaseMixture` where the reported `n_iter_` was
missing an iteration. It affected :class:`mixture.GaussianMixture` and
:class:`mixture.BayesianGaussianMixture`. :issue:`10740` by :user:`Erich
Schubert <kno10>` and :user:`Guillaume Lemaitre <glemaitre>`.
- |Fix| Fixed a bug in `mixture.BaseMixture` and its subclasses
:class:`mixture.GaussianMixture` and :class:`mixture.BayesianGaussianMixture`
where the ``lower_bound_`` was not the max lower bound across all
initializations (when ``n_init > 1``), but just the lower bound of the last
initialization. :issue:`10869` by :user:`Aurélien Géron <ageron>`.
:mod:`sklearn.model_selection`
..............................
- |Feature| Add `return_estimator` parameter in
:func:`model_selection.cross_validate` to return estimators fitted on each
split. :issue:`9686` by :user:`Aurélien Bellet <bellet>`.
- |Feature| New ``refit_time_`` attribute will be stored in
:class:`model_selection.GridSearchCV` and
:class:`model_selection.RandomizedSearchCV` if ``refit`` is set to ``True``.
This will allow measuring the complete time it takes to perform
hyperparameter optimization and refitting the best model on the whole
dataset. :issue:`11310` by :user:`Matthias Feurer <mfeurer>`.
- |Feature| Expose `error_score` parameter in
:func:`model_selection.cross_validate`,
:func:`model_selection.cross_val_score`,
:func:`model_selection.learning_curve` and
:func:`model_selection.validation_curve` to control the behavior triggered
when an error occurs in `model_selection._fit_and_score`.
:issue:`11576` by :user:`Samuel O. Ronsin <samronsin>`.
- |Feature| `BaseSearchCV` now has an experimental, private interface to
support customized parameter search strategies, through its ``_run_search``
method. See the implementations in :class:`model_selection.GridSearchCV` and
:class:`model_selection.RandomizedSearchCV` and please provide feedback if
you use this. Note that we do not assure the stability of this API beyond
version 0.20. :issue:`9599` by `Joel Nothman`_
- |Enhancement| Add improved error message in
:func:`model_selection.cross_val_score` when multiple metrics are passed in
``scoring`` keyword. :issue:`11006` by :user:`Ming Li <minggli>`.
- |API| The default number of cross-validation folds ``cv`` and the default
number of splits ``n_splits`` in the :class:`model_selection.KFold`-like
splitters will change from 3 to 5 in 0.22 as 3-fold has a lot of variance.
:issue:`11557` by :user:`Alexandre Boucaud <aboucaud>`.
- |API| The default of ``iid`` parameter of :class:`model_selection.GridSearchCV`
and :class:`model_selection.RandomizedSearchCV` will change from ``True`` to
``False`` in version 0.22 to correspond to the standard definition of
cross-validation, and the parameter will be removed in version 0.24
altogether. This parameter is of greatest practical significance where the
sizes of different test sets in cross-validation were very unequal, i.e. in
group-based CV strategies. :issue:`9085` by :user:`Laurent Direr <ldirer>`
and `Andreas Müller`_.
- |API| The default value of the ``error_score`` parameter in
:class:`model_selection.GridSearchCV` and
:class:`model_selection.RandomizedSearchCV` will change to ``np.NaN`` in
version 0.22. :issue:`10677` by :user:`Kirill Zhdanovich <Zhdanovich>`.
- |API| Changed ValueError exception raised in
:class:`model_selection.ParameterSampler` to a UserWarning for case where the
class is instantiated with a greater value of ``n_iter`` than the total space
of parameters in the parameter grid. ``n_iter`` now acts as an upper bound on
iterations. :issue:`10982` by :user:`Juliet Lawton <julietcl>`
- |API| Invalid input for :class:`model_selection.ParameterGrid` now
raises TypeError.
:issue:`10928` by :user:`Solutus Immensus <solutusimmensus>`
:mod:`sklearn.multioutput`
..........................
- |MajorFeature| Added :class:`multioutput.RegressorChain` for multi-target
regression. :issue:`9257` by :user:`Kumar Ashutosh <thechargedneutron>`.
:mod:`sklearn.naive_bayes`
..........................
- |MajorFeature| Added :class:`naive_bayes.ComplementNB`, which implements the
Complement Naive Bayes classifier described in Rennie et al. (2003).
:issue:`8190` by :user:`Michael A. Alcorn <airalcorn2>`.
- |Feature| Add `var_smoothing` parameter in :class:`naive_bayes.GaussianNB`
to give a precise control over variances calculation.
:issue:`9681` by :user:`Dmitry Mottl <Mottl>`.
- |Fix| Fixed a bug in :class:`naive_bayes.GaussianNB` which incorrectly
raised error for prior list which summed to 1.
:issue:`10005` by :user:`Gaurav Dhingra <gxyd>`.
- |Fix| Fixed a bug in :class:`naive_bayes.MultinomialNB` which did not accept
vector valued pseudocounts (alpha).
:issue:`10346` by :user:`Tobias Madsen <TobiasMadsen>`
:mod:`sklearn.neighbors`
........................
- |Efficiency| :class:`neighbors.RadiusNeighborsRegressor` and
:class:`neighbors.RadiusNeighborsClassifier` are now
parallelized according to ``n_jobs`` regardless of ``algorithm``.
:issue:`10887` by :user:`Joël Billaud <recamshak>`.
- |Efficiency| :mod:`sklearn.neighbors` query methods are now more
memory efficient when ``algorithm='brute'``.
:issue:`11136` by `Joel Nothman`_ and :user:`Aman Dalmia <dalmia>`.
- |Feature| Add ``sample_weight`` parameter to the fit method of
:class:`neighbors.KernelDensity` to enable weighting in kernel density
estimation.
:issue:`4394` by :user:`Samuel O. Ronsin <samronsin>`.
- |Feature| Novelty detection with :class:`neighbors.LocalOutlierFactor`:
Add a ``novelty`` parameter to :class:`neighbors.LocalOutlierFactor`. When
``novelty`` is set to True, :class:`neighbors.LocalOutlierFactor` can then
be used for novelty detection, i.e. predict on new unseen data. Available
prediction methods are ``predict``, ``decision_function`` and
``score_samples``. By default, ``novelty`` is set to ``False``, and only
the ``fit_predict`` method is available.
By :user:`Albert Thomas <albertcthomas>`.
- |Fix| Fixed a bug in :class:`neighbors.NearestNeighbors` where fitting a
NearestNeighbors model fails when a) the distance metric used is a
callable and b) the input to the NearestNeighbors model is sparse.
:issue:`9579` by :user:`Thomas Kober <tttthomasssss>`.
- |Fix| Fixed a bug so ``predict`` in
:class:`neighbors.RadiusNeighborsRegressor` can handle empty neighbor set
when using non uniform weights. Also raises a new warning when no neighbors
are found for samples. :issue:`9655` by :user:`Andreas Bjerre-Nielsen
<abjer>`.
- |Fix| |Efficiency| Fixed a bug in ``KDTree`` construction that results in
faster construction and querying times.
:issue:`11556` by :user:`Jake VanderPlas <jakevdp>`
- |Fix| Fixed a bug in :class:`neighbors.KDTree` and :class:`neighbors.BallTree` where
pickled tree objects would change their type to the super class `BinaryTree`.
:issue:`11774` by :user:`Nicolas Hug <NicolasHug>`.
:mod:`sklearn.neural_network`
.............................
- |Feature| Add `n_iter_no_change` parameter in
`neural_network.BaseMultilayerPerceptron`,
:class:`neural_network.MLPRegressor`, and
:class:`neural_network.MLPClassifier` to give control over
maximum number of epochs to not meet ``tol`` improvement.
:issue:`9456` by :user:`Nicholas Nadeau <nnadeau>`.
- |Fix| Fixed a bug in `neural_network.BaseMultilayerPerceptron`,
:class:`neural_network.MLPRegressor`, and
:class:`neural_network.MLPClassifier` with new ``n_iter_no_change``
parameter now at 10 from previously hardcoded 2.
:issue:`9456` by :user:`Nicholas Nadeau <nnadeau>`.
- |Fix| Fixed a bug in :class:`neural_network.MLPRegressor` where fitting
quit unexpectedly early due to local minima or fluctuations.
:issue:`9456` by :user:`Nicholas Nadeau <nnadeau>`
:mod:`sklearn.pipeline`
.......................
- |Feature| The ``predict`` method of :class:`pipeline.Pipeline` now passes
keyword arguments on to the pipeline's last estimator, enabling the use of
parameters such as ``return_std`` in a pipeline with caution.
:issue:`9304` by :user:`Breno Freitas <brenolf>`.
- |API| :class:`pipeline.FeatureUnion` now supports ``'drop'`` as a transformer
to drop features. :issue:`11144` by :user:`Thomas Fan <thomasjpfan>`.
:mod:`sklearn.preprocessing`
............................
- |MajorFeature| Expanded :class:`preprocessing.OneHotEncoder` to allow to
encode categorical string features as a numeric array using a one-hot (or
dummy) encoding scheme, and added :class:`preprocessing.OrdinalEncoder` to
convert to ordinal integers. Those two classes now handle encoding of all
feature types (also handles string-valued features) and derives the
categories based on the unique values in the features instead of the maximum
value in the features. :issue:`9151` and :issue:`10521` by :user:`Vighnesh
Birodkar <vighneshbirodkar>` and `Joris Van den Bossche`_.
- |MajorFeature| Added :class:`preprocessing.KBinsDiscretizer` for turning
continuous features into categorical or one-hot encoded
features. :issue:`7668`, :issue:`9647`, :issue:`10195`,
:issue:`10192`, :issue:`11272`, :issue:`11467` and :issue:`11505`.
by :user:`Henry Lin <hlin117>`, `Hanmin Qin`_,
`Tom Dupre la Tour`_ and :user:`Giovanni Giuseppe Costa <ggc87>`.
- |MajorFeature| Added :class:`preprocessing.PowerTransformer`, which
implements the Yeo-Johnson and Box-Cox power transformations. Power
transformations try to find a set of feature-wise parametric transformations
to approximately map data to a Gaussian distribution centered at zero and
with unit variance. This is useful as a variance-stabilizing transformation
in situations where normality and homoscedasticity are desirable.
:issue:`10210` by :user:`Eric Chang <chang>` and :user:`Maniteja
Nandana <maniteja123>`, and :issue:`11520` by :user:`Nicolas Hug
<nicolashug>`.
- |MajorFeature| NaN values are ignored and handled in the following
preprocessing methods:
:class:`preprocessing.MaxAbsScaler`,
:class:`preprocessing.MinMaxScaler`,
:class:`preprocessing.RobustScaler`,
:class:`preprocessing.StandardScaler`,
:class:`preprocessing.PowerTransformer`,
:class:`preprocessing.QuantileTransformer` classes and
:func:`preprocessing.maxabs_scale`,
:func:`preprocessing.minmax_scale`,
:func:`preprocessing.robust_scale`,
:func:`preprocessing.scale`,
:func:`preprocessing.power_transform`,
:func:`preprocessing.quantile_transform` functions respectively addressed in
issues :issue:`11011`, :issue:`11005`, :issue:`11308`, :issue:`11206`,
:issue:`11306`, and :issue:`10437`.
By :user:`Lucija Gregov <LucijaGregov>` and
:user:`Guillaume Lemaitre <glemaitre>`.
- |Feature| :class:`preprocessing.PolynomialFeatures` now supports sparse
input. :issue:`10452` by :user:`Aman Dalmia <dalmia>` and `Joel Nothman`_.
- |Feature| :class:`preprocessing.RobustScaler` and
:func:`preprocessing.robust_scale` can be fitted using sparse matrices.
:issue:`11308` by :user:`Guillaume Lemaitre <glemaitre>`.
- |Feature| :class:`preprocessing.OneHotEncoder` now supports the
`get_feature_names` method to obtain the transformed feature names.
:issue:`10181` by :user:`Nirvan Anjirbag <Nirvan101>` and
`Joris Van den Bossche`_.
- |Feature| A parameter ``check_inverse`` was added to
:class:`preprocessing.FunctionTransformer` to ensure that ``func`` and
``inverse_func`` are the inverse of each other.
:issue:`9399` by :user:`Guillaume Lemaitre <glemaitre>`.
- |Feature| The ``transform`` method of :class:`sklearn.preprocessing.MultiLabelBinarizer`
now ignores any unknown classes. A warning is raised stating the unknown classes
classes found which are ignored.
:issue:`10913` by :user:`Rodrigo Agundez <rragundez>`.
- |Fix| Fixed bugs in :class:`preprocessing.LabelEncoder` which would
sometimes throw errors when ``transform`` or ``inverse_transform`` was called
with empty arrays. :issue:`10458` by :user:`Mayur Kulkarni <maykulkarni>`.
- |Fix| Fix ValueError in :class:`preprocessing.LabelEncoder` when using
``inverse_transform`` on unseen labels. :issue:`9816` by :user:`Charlie Newey
<newey01c>`.
- |Fix| Fix bug in :class:`preprocessing.OneHotEncoder` which discarded the
``dtype`` when returning a sparse matrix output.
:issue:`11042` by :user:`Daniel Morales <DanielMorales9>`.
- |Fix| Fix ``fit`` and ``partial_fit`` in
:class:`preprocessing.StandardScaler` in the rare case when ``with_mean=False``
and `with_std=False` which was crashing by calling ``fit`` more than once and
giving inconsistent results for ``mean_`` whether the input was a sparse or a
dense matrix. ``mean_`` will be set to ``None`` with both sparse and dense
inputs. ``n_samples_seen_`` will be also reported for both input types.
:issue:`11235` by :user:`Guillaume Lemaitre <glemaitre>`.
- |API| Deprecate ``n_values`` and ``categorical_features`` parameters and
``active_features_``, ``feature_indices_`` and ``n_values_`` attributes
of :class:`preprocessing.OneHotEncoder`. The ``n_values`` parameter can be
replaced with the new ``categories`` parameter, and the attributes with the
new ``categories_`` attribute. Selecting the categorical features with
the ``categorical_features`` parameter is now better supported using the
:class:`compose.ColumnTransformer`.
:issue:`10521` by `Joris Van den Bossche`_.
- |API| Deprecate `preprocessing.Imputer` and move
the corresponding module to :class:`impute.SimpleImputer`.
:issue:`9726` by :user:`Kumar Ashutosh
<thechargedneutron>`.
- |API| The ``axis`` parameter that was in
`preprocessing.Imputer` is no longer present in
:class:`impute.SimpleImputer`. The behavior is equivalent
to ``axis=0`` (impute along columns). Row-wise
imputation can be performed with FunctionTransformer
(e.g., ``FunctionTransformer(lambda X:
SimpleImputer().fit_transform(X.T).T)``). :issue:`10829`
by :user:`Guillaume Lemaitre <glemaitre>` and
:user:`Gilberto Olimpio <gilbertoolimpio>`.
- |API| The NaN marker for the missing values has been changed
between the `preprocessing.Imputer` and the
`impute.SimpleImputer`.
``missing_values='NaN'`` should now be
``missing_values=np.nan``. :issue:`11211` by
:user:`Jeremie du Boisberranger <jeremiedbb>`.
- |API| In :class:`preprocessing.FunctionTransformer`, the default of
``validate`` will be from ``True`` to ``False`` in 0.22.
:issue:`10655` by :user:`Guillaume Lemaitre <glemaitre>`.
:mod:`sklearn.svm`
..................
- |Fix| Fixed a bug in :class:`svm.SVC` where when the argument ``kernel`` is
unicode in Python2, the ``predict_proba`` method was raising an
unexpected TypeError given dense inputs.
:issue:`10412` by :user:`Jiongyan Zhang <qmick>`.
- |API| Deprecate ``random_state`` parameter in :class:`svm.OneClassSVM` as
the underlying implementation is not random.
:issue:`9497` by :user:`Albert Thomas <albertcthomas>`.
- |API| The default value of ``gamma`` parameter of :class:`svm.SVC`,
:class:`~svm.NuSVC`, :class:`~svm.SVR`, :class:`~svm.NuSVR`,
:class:`~svm.OneClassSVM` will change from ``'auto'`` to ``'scale'`` in
version 0.22 to account better for unscaled features. :issue:`8361` by
:user:`Gaurav Dhingra <gxyd>` and :user:`Ting Neo <neokt>`.
:mod:`sklearn.tree`
...................
- |Enhancement| Although private (and hence not assured API stability),
`tree._criterion.ClassificationCriterion` and
`tree._criterion.RegressionCriterion` may now be cimported and
extended. :issue:`10325` by :user:`Camil Staps <camilstaps>`.
- |Fix| Fixed a bug in `tree.BaseDecisionTree` with `splitter="best"`
where split threshold could become infinite when values in X were
near infinite. :issue:`10536` by :user:`Jonathan Ohayon <Johayon>`.
- |Fix| Fixed a bug in `tree.MAE` to ensure sample weights are being
used during the calculation of tree MAE impurity. Previous behaviour could
cause suboptimal splits to be chosen since the impurity calculation
considered all samples to be of equal weight importance.
:issue:`11464` by :user:`John Stott <JohnStott>`.
:mod:`sklearn.utils`
....................
- |Feature| :func:`utils.check_array` and :func:`utils.check_X_y` now have
``accept_large_sparse`` to control whether scipy.sparse matrices with 64-bit
indices should be rejected.
:issue:`11327` by :user:`Karan Dhingra <kdhingra307>` and `Joel Nothman`_.
- |Efficiency| |Fix| Avoid copying the data in :func:`utils.check_array` when
the input data is a memmap (and ``copy=False``). :issue:`10663` by
:user:`Arthur Mensch <arthurmensch>` and :user:`Loïc Estève <lesteve>`.
- |API| :func:`utils.check_array` yield a ``FutureWarning`` indicating
that arrays of bytes/strings will be interpreted as decimal numbers
beginning in version 0.22. :issue:`10229` by :user:`Ryan Lee <rtlee9>`
Multiple modules
................
- |Feature| |API| More consistent outlier detection API:
Add a ``score_samples`` method in :class:`svm.OneClassSVM`,
:class:`ensemble.IsolationForest`, :class:`neighbors.LocalOutlierFactor`,
:class:`covariance.EllipticEnvelope`. It allows to access raw score
functions from original papers. A new ``offset_`` parameter allows to link
``score_samples`` and ``decision_function`` methods.
The ``contamination`` parameter of :class:`ensemble.IsolationForest` and
:class:`neighbors.LocalOutlierFactor` ``decision_function`` methods is used
to define this ``offset_`` such that outliers (resp. inliers) have negative (resp.
positive) ``decision_function`` values. By default, ``contamination`` is
kept unchanged to 0.1 for a deprecation period. In 0.22, it will be set to "auto",
thus using method-specific score offsets.
In :class:`covariance.EllipticEnvelope` ``decision_function`` method, the
``raw_values`` parameter is deprecated as the shifted Mahalanobis distance
will be always returned in 0.22. :issue:`9015` by `Nicolas Goix`_.
- |Feature| |API| A ``behaviour`` parameter has been introduced in :class:`ensemble.IsolationForest`
to ensure backward compatibility.
In the old behaviour, the ``decision_function`` is independent of the ``contamination``
parameter. A threshold attribute depending on the ``contamination`` parameter is thus
used.
In the new behaviour the ``decision_function`` is dependent on the ``contamination``
parameter, in such a way that 0 becomes its natural threshold to detect outliers.
Setting behaviour to "old" is deprecated and will not be possible in version 0.22.
Beside, the behaviour parameter will be removed in 0.24.
:issue:`11553` by `Nicolas Goix`_.
- |API| Added convergence warning to :class:`svm.LinearSVC` and
:class:`linear_model.LogisticRegression` when ``verbose`` is set to 0.
:issue:`10881` by :user:`Alexandre Sevin <AlexandreSev>`.
- |API| Changed warning type from :class:`UserWarning` to
:class:`exceptions.ConvergenceWarning` for failing convergence in
`linear_model.logistic_regression_path`,
:class:`linear_model.RANSACRegressor`, :func:`linear_model.ridge_regression`,
:class:`gaussian_process.GaussianProcessRegressor`,
:class:`gaussian_process.GaussianProcessClassifier`,
:func:`decomposition.fastica`, :class:`cross_decomposition.PLSCanonical`,
:class:`cluster.AffinityPropagation`, and :class:`cluster.Birch`.
:issue:`10306` by :user:`Jonathan Siebert <jotasi>`.
Miscellaneous
.............
- |MajorFeature| A new configuration parameter, ``working_memory`` was added
to control memory consumption limits in chunked operations, such as the new
:func:`metrics.pairwise_distances_chunked`. See :ref:`working_memory`.
:issue:`10280` by `Joel Nothman`_ and :user:`Aman Dalmia <dalmia>`.
- |Feature| The version of :mod:`joblib` bundled with Scikit-learn is now 0.12.
This uses a new default multiprocessing implementation, named `loky
<https://github.com/tomMoral/loky>`_. While this may incur some memory and
communication overhead, it should provide greater cross-platform stability
than relying on Python standard library multiprocessing. :issue:`11741` by
the Joblib developers, especially :user:`Thomas Moreau <tomMoral>` and
`Olivier Grisel`_.
- |Feature| An environment variable to use the site joblib instead of the
vendored one was added (:ref:`environment_variable`). The main API of joblib
is now exposed in :mod:`sklearn.utils`.
:issue:`11166` by `Gael Varoquaux`_.
- |Feature| Add almost complete PyPy 3 support. Known unsupported
functionalities are :func:`datasets.load_svmlight_file`,
:class:`feature_extraction.FeatureHasher` and
:class:`feature_extraction.text.HashingVectorizer`. For running on PyPy,
PyPy3-v5.10+, Numpy 1.14.0+, and scipy 1.1.0+ are required.
:issue:`11010` by :user:`Ronan Lamy <rlamy>` and `Roman Yurchak`_.
- |Feature| A utility method :func:`sklearn.show_versions()` was added to
print out information relevant for debugging. It includes the user system,
the Python executable, the version of the main libraries and BLAS binding
information. :issue:`11596` by :user:`Alexandre Boucaud <aboucaud>`
- |Fix| Fixed a bug when setting parameters on meta-estimator, involving both
a wrapped estimator and its parameter. :issue:`9999` by :user:`Marcus Voss
<marcus-voss>` and `Joel Nothman`_.
- |Fix| Fixed a bug where calling :func:`sklearn.base.clone` was not thread
safe and could result in a "pop from empty list" error. :issue:`9569`
by `Andreas Müller`_.
- |API| The default value of ``n_jobs`` is changed from ``1`` to ``None`` in
all related functions and classes. ``n_jobs=None`` means ``unset``. It will
generally be interpreted as ``n_jobs=1``, unless the current
``joblib.Parallel`` backend context specifies otherwise (See
:term:`Glossary <n_jobs>` for additional information). Note that this change
happens immediately (i.e., without a deprecation cycle).
:issue:`11741` by `Olivier Grisel`_.
- |Fix| Fixed a bug in validation helpers where passing a Dask DataFrame results
in an error. :issue:`12462` by :user:`Zachariah Miller <zwmiller>`
Changes to estimator checks
---------------------------
These changes mostly affect library developers.
- Checks for transformers now apply if the estimator implements
:term:`transform`, regardless of whether it inherits from
:class:`sklearn.base.TransformerMixin`. :issue:`10474` by `Joel Nothman`_.
- Classifiers are now checked for consistency between :term:`decision_function`
and categorical predictions.
:issue:`10500` by :user:`Narine Kokhlikyan <NarineK>`.
- Allow tests in :func:`utils.estimator_checks.check_estimator` to test functions
that accept pairwise data.
:issue:`9701` by :user:`Kyle Johnson <gkjohns>`
- Allow :func:`utils.estimator_checks.check_estimator` to check that there is no
private settings apart from parameters during estimator initialization.
:issue:`9378` by :user:`Herilalaina Rakotoarison <herilalaina>`
- The set of checks in :func:`utils.estimator_checks.check_estimator` now includes a
``check_set_params`` test which checks that ``set_params`` is equivalent to
passing parameters in ``__init__`` and warns if it encounters parameter
validation. :issue:`7738` by :user:`Alvin Chiang <absolutelyNoWarranty>`
- Add invariance tests for clustering metrics. :issue:`8102` by :user:`Ankita
Sinha <anki08>` and :user:`Guillaume Lemaitre <glemaitre>`.
- Add ``check_methods_subset_invariance`` to
:func:`~utils.estimator_checks.check_estimator`, which checks that
estimator methods are invariant if applied to a data subset.
:issue:`10428` by :user:`Jonathan Ohayon <Johayon>`
- Add tests in :func:`utils.estimator_checks.check_estimator` to check that an
estimator can handle read-only memmap input data. :issue:`10663` by
:user:`Arthur Mensch <arthurmensch>` and :user:`Loïc Estève <lesteve>`.
- ``check_sample_weights_pandas_series`` now uses 8 rather than 6 samples
to accommodate for the default number of clusters in :class:`cluster.KMeans`.
:issue:`10933` by :user:`Johannes Hansen <jnhansen>`.
- Estimators are now checked for whether ``sample_weight=None`` equates to
``sample_weight=np.ones(...)``.
:issue:`11558` by :user:`Sergul Aydore <sergulaydore>`.
Code and Documentation Contributors
-----------------------------------
Thanks to everyone who has contributed to the maintenance and improvement of the
project since version 0.19, including:
211217613, Aarshay Jain, absolutelyNoWarranty, Adam Greenhall, Adam Kleczewski,
Adam Richie-Halford, adelr, AdityaDaflapurkar, Adrin Jalali, Aidan Fitzgerald,
aishgrt1, Akash Shivram, Alan Liddell, Alan Yee, Albert Thomas, Alexander
Lenail, Alexander-N, Alexandre Boucaud, Alexandre Gramfort, Alexandre Sevin,
Alex Egg, Alvaro Perez-Diaz, Amanda, Aman Dalmia, Andreas Bjerre-Nielsen,
Andreas Mueller, Andrew Peng, Angus Williams, Aniruddha Dave, annaayzenshtat,
Anthony Gitter, Antonio Quinonez, Anubhav Marwaha, Arik Pamnani, Arthur Ozga,
Artiem K, Arunava, Arya McCarthy, Attractadore, Aurélien Bellet, Aurélien
Geron, Ayush Gupta, Balakumaran Manoharan, Bangda Sun, Barry Hart, Bastian
Venthur, Ben Lawson, Benn Roth, Breno Freitas, Brent Yi, brett koonce, Caio
Oliveira, Camil Staps, cclauss, Chady Kamar, Charlie Brummitt, Charlie Newey,
chris, Chris, Chris Catalfo, Chris Foster, Chris Holdgraf, Christian Braune,
Christian Hirsch, Christian Hogan, Christopher Jenness, Clement Joudet, cnx,
cwitte, Dallas Card, Dan Barkhorn, Daniel, Daniel Ferreira, Daniel Gomez,
Daniel Klevebring, Danielle Shwed, Daniel Mohns, Danil Baibak, Darius Morawiec,
David Beach, David Burns, David Kirkby, David Nicholson, David Pickup, Derek,
Didi Bar-Zev, diegodlh, Dillon Gardner, Dillon Niederhut, dilutedsauce,
dlovell, Dmitry Mottl, Dmitry Petrov, Dor Cohen, Douglas Duhaime, Ekaterina
Tuzova, Eric Chang, Eric Dean Sanchez, Erich Schubert, Eunji, Fang-Chieh Chou,
FarahSaeed, felix, Félix Raimundo, fenx, filipj8, FrankHui, Franz Wompner,
Freija Descamps, frsi, Gabriele Calvo, Gael Varoquaux, Gaurav Dhingra, Georgi
Peev, Gil Forsyth, Giovanni Giuseppe Costa, gkevinyen5418, goncalo-rodrigues,
Gryllos Prokopis, Guillaume Lemaitre, Guillaume "Vermeille" Sanchez, Gustavo De
Mari Pereira, hakaa1, Hanmin Qin, Henry Lin, Hong, Honghe, Hossein Pourbozorg,
Hristo, Hunan Rostomyan, iampat, Ivan PANICO, Jaewon Chung, Jake VanderPlas,
jakirkham, James Bourbeau, James Malcolm, Jamie Cox, Jan Koch, Jan Margeta, Jan
Schlüter, janvanrijn, Jason Wolosonovich, JC Liu, Jeb Bearer, jeremiedbb, Jimmy
Wan, Jinkun Wang, Jiongyan Zhang, jjabl, jkleint, Joan Massich, Joël Billaud,
Joel Nothman, Johannes Hansen, JohnStott, Jonatan Samoocha, Jonathan Ohayon,
Jörg Döpfert, Joris Van den Bossche, Jose Perez-Parras Toledano, josephsalmon,
jotasi, jschendel, Julian Kuhlmann, Julien Chaumond, julietcl, Justin Shenk,
Karl F, Kasper Primdal Lauritzen, Katrin Leinweber, Kirill, ksemb, Kuai Yu,
Kumar Ashutosh, Kyeongpil Kang, Kye Taylor, kyledrogo, Leland McInnes, Léo DS,
Liam Geron, Liutong Zhou, Lizao Li, lkjcalc, Loic Esteve, louib, Luciano Viola,
Lucija Gregov, Luis Osa, Luis Pedro Coelho, Luke M Craig, Luke Persola, Mabel,
Mabel Villalba, Maniteja Nandana, MarkIwanchyshyn, Mark Roth, Markus Müller,
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