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.
sklearn.cluster
¶
- Fix Fixed a bug in
cluster.KMeans
where KMeans++ initialisation could rarely result in an IndexError. #11756 by Joel Nothman.
sklearn.compose
¶
- Fix Fixed an issue in
compose.ColumnTransformer
where using DataFrames whose column order differs between :func:fit
and :func:transform
could lead to silently passing incorrect columns to theremainder
transformer. :pr:`14237` by Andreas Schuderer <schuderer>.
sklearn.decomposition
¶
- Fix Fixed a bug in
cross_decomposition.CCA
improving numerical stability when Y is close to zero. :pr:`13903` by `Thomas Fan`_.
sklearn.model_selection
¶
- Fix Fixed a bug where
model_selection.StratifiedKFold
shuffles each class’s samples with the samerandom_state
, makingshuffle=True
ineffective. #13124 by Hanmin Qin.
sklearn.neighbors
¶
- Fix Fixed a bug in
neighbors.KernelDensity
which could not be restored from a pickle ifsample_weight
had been used. #13772 by Aditya Vyas.
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¶
sklearn.cluster
¶
- Fix Fixed a bug in
cluster.KMeans
where computation was single threaded when n_jobs > 1 or n_jobs = -1. #12949 by Prabakaran Kumaresshan.
sklearn.compose
¶
- Fix Fixed a bug in
compose.ColumnTransformer
to handle negative indexes in the columns list of the transformers. #12946 by Pierre Tallotte.
sklearn.covariance
¶
- Fix Fixed a regression in
covariance.graphical_lasso
so that the case n_features=2 is handled correctly. #13276 by Aurélien Bellet.
sklearn.decomposition
¶
- Fix Fixed a bug in
decomposition.sparse_encode
where computation was single threaded when n_jobs > 1 or n_jobs = -1. #13005 by Prabakaran Kumaresshan.
sklearn.datasets
¶
- Efficiency
sklearn.datasets.fetch_openml
now loads data by streaming, avoiding high memory usage. #13312 by Joris Van den Bossche.
sklearn.feature_extraction
¶
- Fix Fixed a bug in
feature_extraction.text.CountVectorizer
which would result in the sparse feature matrix having conflicting indptr and indices precisions under very large vocabularies. #11295 by Gabriel Vacaliuc.
sklearn.impute
¶
- Fix add support for non-numeric data in
sklearn.impute.MissingIndicator
which was not supported whilesklearn.impute.SimpleImputer
was supporting this for some imputation strategies. #13046 by Guillaume Lemaitre.
sklearn.linear_model
¶
- Fix Fixed a bug in
linear_model.MultiTaskElasticNet
andlinear_model.MultiTaskLasso
which were breaking whenwarm_start = True
. #12360 by Aakanksha Joshi.
sklearn.preprocessing
¶
- Fix Fixed a bug in
preprocessing.KBinsDiscretizer
wherestrategy='kmeans'
fails with an error during transformation due to unsorted bin edges. #13134 by Sandro Casagrande. - Fix Fixed a bug in
preprocessing.OneHotEncoder
where the deprecation ofcategorical_features
was handled incorrectly in combination withhandle_unknown='ignore'
. #12881 by Joris Van den Bossche. - Fix Bins whose width are too small (i.e., <= 1e-8) are removed
with a warning in
preprocessing.KBinsDiscretizer
. #13165 by Hanmin Qin.
sklearn.svm
¶
- Fix Fixed a bug in
svm.SVC
,svm.NuSVC
,svm.SVR
,svm.NuSVR
andsvm.OneClassSVM
where thescale
option of parametergamma
is erroneously defined as1 / (n_features * X.std())
. It’s now defined as1 / (n_features * X.var())
. #13221 by Hanmin Qin.
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
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.
sklearn.neighbors
whenmetric=='jaccard'
(bug fix)- use of
'seuclidean'
or'mahalanobis'
metrics in some cases (bug fix)
Changelog¶
sklearn.compose
¶
- Fix Fixed an issue in
compose.make_column_transformer
which raises unexpected error when columns is pandas Index or pandas Series. #12704 by Hanmin Qin.
sklearn.metrics
¶
- Fix Fixed a bug in
metrics.pairwise_distances
andmetrics.pairwise_distances_chunked
where parametersV
of"seuclidean"
andVI
of"mahalanobis"
metrics were computed after the data was split into chunks instead of being pre-computed on whole data. #12701 by Jeremie du Boisberranger.
sklearn.neighbors
¶
- Fix Fixed
sklearn.neighbors.DistanceMetric
jaccard distance function to return 0 when two all-zero vectors are compared. #12685 by Thomas Fan.
sklearn.utils
¶
- Fix Calling
utils.check_array
on pandas.Series with categorical data, which raised an error in 0.20.0, now returns the expected output again. #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
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.
decomposition.IncrementalPCA
(bug fix)
Changelog¶
sklearn.cluster
¶
- Efficiency make
cluster.MeanShift
no longer try to do nested parallelism as the overhead would hurt performance significantly whenn_jobs > 1
. #12159 by Olivier Grisel. - Fix Fixed a bug in
cluster.DBSCAN
with precomputed sparse neighbors graph, which would add explicitly zeros on the diagonal even when already present. #12105 by Tom Dupre la Tour.
sklearn.compose
¶
- Fix Fixed an issue in
compose.ColumnTransformer
when stacking columns with types not convertible to a numeric. #11912 by Adrin Jalali. - API Change
compose.ColumnTransformer
now applies thesparse_threshold
even if all transformation results are sparse. #12304 by Andreas Müller. - API Change
compose.make_column_transformer
now expects(transformer, columns)
instead of(columns, transformer)
to keep consistent withcompose.ColumnTransformer
. #12339 by Adrin Jalali.
sklearn.datasets
¶
- Fix
datasets.fetch_openml
to correctly use the local cache. #12246 by Jan N. van Rijn. - Fix
datasets.fetch_openml
to correctly handle ignore attributes and row id attributes. #12330 by Jan N. van Rijn. - Fix Fixed integer overflow in
datasets.make_classification
for values ofn_informative
parameter larger than 64. #10811 by Roman Feldbauer. - Fix Fixed olivetti faces dataset
DESCR
attribute to point to the right location indatasets.fetch_olivetti_faces
. #12441 by Jérémie du Boisberranger - Fix
datasets.fetch_openml
to retry downloading when reading from local cache fails. #12517 by Thomas Fan.
sklearn.decomposition
¶
- Fix Fixed a regression in
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. #12234 by Ming Li.
sklearn.ensemble
¶
- Fix Fixed a bug mostly affecting
ensemble.RandomForestClassifier
whereclass_weight='balanced_subsample'
failed with more than 32 classes. #12165 by Joel Nothman. - Fix Fixed a bug affecting
ensemble.BaggingClassifier
,ensemble.BaggingRegressor
andensemble.IsolationForest
, wheremax_features
was sometimes rounded down to zero. #12388 by Connor Tann.
sklearn.feature_extraction
¶
- Fix Fixed a regression in v0.20.0 where
feature_extraction.text.CountVectorizer
and other text vectorizers could error during stop words validation with custom preprocessors or tokenizers. #12393 by Roman Yurchak.
sklearn.linear_model
¶
- Fix
linear_model.SGDClassifier
and variants withearly_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. #12122 by Olivier Grisel. - Fix Fixed a bug affecting
SGDClassifier
in the multiclass case. Each one-versus-all step is run in ajoblib.Parallel
call and mutating a common parameter, causing a segmentation fault if called within a backend using processes and not threads. We now userequire=sharedmem
at thejoblib.Parallel
instance creation. #12518 by Pierre Glaser and Olivier Grisel.
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”. #12481 by Jérémie du Boisberranger. - Fix Fixed a bug in
metrics.pairwise.pairwise_distances_chunked
which didn’t ensure the diagonal is zero for euclidean distances. #12612 by Andreas Müller. - API Change The
metrics.calinski_harabaz_score
has been renamed tometrics.calinski_harabasz_score
and will be removed in version 0.23. #12211 by Lisa Thomas, Mark Hannel and Melissa Ferrari.
sklearn.mixture
¶
- Fix Ensure that the
fit_predict
method ofmixture.GaussianMixture
andmixture.BayesianGaussianMixture
always yield assignments consistent withfit
followed bypredict
even if the convergence criterion is too loose or not met. #12451 by Olivier Grisel.
sklearn.neighbors
¶
- Fix force the parallelism backend to
threading
forneighbors.KDTree
andneighbors.BallTree
in Python 2.7 to avoid pickling errors caused by the serialization of their methods. #12171 by Thomas Moreau.
sklearn.preprocessing
¶
- Fix Fixed bug in
preprocessing.OrdinalEncoder
when passing manually specified categories. #12365 by Joris Van den Bossche. - Fix Fixed bug in
preprocessing.KBinsDiscretizer
where thetransform
method mutates the_encoder
attribute. Thetransform
method is now thread safe. #12514 by Hanmin Qin. - Fix Fixed a bug in
preprocessing.PowerTransformer
where the Yeo-Johnson transform was incorrect for lambda parameters outside of [0, 2] #12522 by Nicolas Hug. - Fix Fixed a bug in
preprocessing.OneHotEncoder
where transform failed when set to ignore unknown numpy strings of different lengths #12471 by Gabriel Marzinotto. - API Change The default value of the
method
argument inpreprocessing.power_transform
will be changed frombox-cox
toyeo-johnson
to matchpreprocessing.PowerTransformer
in version 0.23. A FutureWarning is raised when the default value is used. #12317 by Eric Chang.
sklearn.utils
¶
- Fix Use float64 for mean accumulator to avoid floating point
precision issues in
preprocessing.StandardScaler
anddecomposition.IncrementalPCA
when using float32 datasets. #12338 by bauks. - Fix Calling
utils.check_array
on pandas.Series, which raised an error in 0.20.0, now returns the expected output again. #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+. #12350 by Joel Nothman and Roman Yurchak.
- Fix Make sure to avoid raising
FutureWarning
when callingnp.vstack
with numpy 1.16 and later (use list comprehensions instead of generator expressions in many locations of the scikit-learn code base). #12467 by Olivier Grisel. - API Change Removed all mentions of
sklearn.externals.joblib
, and deprecated joblib methods exposed insklearn.utils
, except forutils.parallel_backend
andutils.register_parallel_backend
, which allow users to configure parallel computation in scikit-learn. Other functionalities are part of joblib. 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. #12345 by Thomas Moreau
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
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.
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.
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 impute
module provides estimators for learning despite missing data.
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
OneHotEncoder
or
OrdinalEncoder
.
TransformedTargetRegressor
helps when the regression target
needs to be transformed to be modeled. PowerTransformer
and KBinsDiscretizer
join
QuantileTransformer
as non-linear transformations.
Beyond this, we have added sample_weight support to several estimators
(including KMeans
, BayesianRidge
and
KernelDensity
) and improved stopping criteria in others
(including MLPRegressor
,
GradientBoostingRegressor
and
SGDRegressor
).
This release is also the first to be accompanied by a Glossary of Common Terms and API Elements 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.
cluster.MeanShift
(bug fix)decomposition.IncrementalPCA
in Python 2 (bug fix)decomposition.SparsePCA
(bug fix)ensemble.GradientBoostingClassifier
(bug fix affecting feature importances)isotonic.IsotonicRegression
(bug fix)linear_model.ARDRegression
(bug fix)linear_model.LogisticRegressionCV
(bug fix)linear_model.OrthogonalMatchingPursuit
(bug fix)linear_model.PassiveAggressiveClassifier
(bug fix)linear_model.PassiveAggressiveRegressor
(bug fix)linear_model.Perceptron
(bug fix)linear_model.SGDClassifier
(bug fix)linear_model.SGDRegressor
(bug fix)metrics.roc_auc_score
(bug fix)metrics.roc_curve
(bug fix)neural_network.BaseMultilayerPerceptron
(bug fix)neural_network.MLPClassifier
(bug fix)neural_network.MLPRegressor
(bug fix)- The v0.19.0 release notes failed to mention a backwards incompatibility with
model_selection.StratifiedKFold
whenshuffle=True
due to #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¶
- #11924:
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. - #9354:
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.
sklearn.cluster
¶
- Major Feature
cluster.AgglomerativeClustering
now supports Single Linkage clustering vialinkage='single'
. #9372 by Leland McInnes and Steve Astels. - Feature
cluster.KMeans
andcluster.MiniBatchKMeans
now support sample weights via new parametersample_weight
infit
function. #10933 by Johannes Hansen. - Efficiency
cluster.KMeans
,cluster.MiniBatchKMeans
andcluster.k_means
passed withalgorithm='full'
now enforces row-major ordering, improving runtime. #10471 by Gaurav Dhingra. - Efficiency
cluster.DBSCAN
now is parallelized according ton_jobs
regardless ofalgorithm
. #8003 by Joël Billaud. - Enhancement
cluster.KMeans
now gives a warning if the number of distinct clusters found is smaller thann_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. #10059 by Christian Braune. - Fix Fixed a bug where the
fit
method ofcluster.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. #9612. By Jonatan Samoocha. - Fix Fixed a bug in
cluster.spectral_clustering
where the normalization of the spectrum was using a division instead of a multiplication. #8129 by Jan Margeta, Guillaume Lemaitre, and Devansh D.. - Fix Fixed a bug in
cluster.k_means_elkan
where the returnediteration
was 1 less than the correct value. Also added the missingn_iter_
attribute in the docstring ofcluster.KMeans
. #11353 by Jeremie du Boisberranger. - Fix Fixed a bug in
cluster.mean_shift
where the assigned labels were not deterministic if there were multiple clusters with the same intensities. #11901 by Adrin Jalali. - API Change Deprecate
pooling_func
unused parameter incluster.AgglomerativeClustering
. #9875 by Kumar Ashutosh.
sklearn.compose
¶
- New module.
- Major Feature Added
compose.ColumnTransformer
, which allows to apply different transformers to different columns of arrays or pandas DataFrames. #9012 by Andreas Müller and Joris Van den Bossche, and #11315 by Thomas Fan. - Major Feature Added the
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. #9041 by Andreas Müller and Guillaume Lemaitre.
sklearn.covariance
¶
- Efficiency Runtime improvements to
covariance.GraphicalLasso
. #9858 by Steven Brown. - API Change The
covariance.graph_lasso
,covariance.GraphLasso
andcovariance.GraphLassoCV
have been renamed tocovariance.graphical_lasso
,covariance.GraphicalLasso
andcovariance.GraphicalLassoCV
respectively and will be removed in version 0.22. #9993 by Artiem Krinitsyn
sklearn.datasets
¶
- Major Feature Added
datasets.fetch_openml
to fetch datasets from OpenML. OpenML is a free, open data sharing platform and will be used instead of mldata as it provides better service availability. #9908 by Andreas Müller and Jan N. van Rijn. - Feature In
datasets.make_blobs
, one can now pass a list to then_samples
parameter to indicate the number of samples to generate per cluster. #8617 by Maskani Filali Mohamed and Konstantinos Katrioplas. - Feature Add
filename
attribute todatasets
that have a CSV file. #9101 by alex-33 and Maskani Filali Mohamed. - Feature
return_X_y
parameter has been added to several dataset loaders. #10774 by Chris Catalfo. - Fix Fixed a bug in
datasets.load_boston
which had a wrong data point. #10795 by Takeshi Yoshizawa. - Fix Fixed a bug in
datasets.load_iris
which had two wrong data points. #11082 by Sadhana Srinivasan and Hanmin Qin. - Fix Fixed a bug in
datasets.fetch_kddcup99
, where data were not properly shuffled. #9731 by Nicolas Goix. - Fix Fixed a bug in
datasets.make_circles
, where no odd number of data points could be generated. #10045 by Christian Braune. - API Change 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. #11466 by Joel Nothman.
sklearn.decomposition
¶
- Feature
decomposition.dict_learning
functions and models now support positivity constraints. This applies to the dictionary and sparse code. #6374 by John Kirkham. - Feature Fix
decomposition.SparsePCA
now exposesnormalize_components
. When set to True, the train and test data are centered with the train mean repsectively 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. #11585 by Ivan Panico. - Efficiency Efficiency improvements in
decomposition.dict_learning
. #11420 and others by John Kirkham. - Fix Fix for uninformative error in
decomposition.IncrementalPCA
: now an error is raised if the number of components is larger than the chosen batch size. Then_components=None
case was adapted accordingly. #6452. By Wally Gauze. - Fix Fixed a bug where the
partial_fit
method ofdecomposition.IncrementalPCA
used integer division instead of float division on Python 2. #9492 by James Bourbeau. - Fix In
decomposition.PCA
selecting a n_components parameter greater than the number of samples now raises an error. Similarly, then_components=None
case now selects the minimum ofn_samples
andn_features
. #8484 by Wally Gauze. - Fix Fixed a bug in
decomposition.PCA
where users will get unexpected error with large datasets whenn_components='mle'
on Python 3 versions. #9886 by Hanmin Qin. - Fix Fixed an underflow in calculating KL-divergence for
decomposition.NMF
#10142 by Tom Dupre la Tour. - Fix Fixed a bug in
decomposition.SparseCoder
when running OMP sparse coding in parallel using read-only memory mapped datastructures. #5956 by Vighnesh Birodkar and Olivier Grisel.
sklearn.discriminant_analysis
¶
- Efficiency Memory usage improvement for
_class_means
and_class_cov
indiscriminant_analysis
. #10898 by Nanxin Chen.
sklearn.dummy
¶
- Feature
dummy.DummyRegressor
now has areturn_std
option in itspredict
method. The returned standard deviations will be zeros. - Feature
dummy.DummyClassifier
anddummy.DummyRegressor
now only require X to be an object with finite length or shape. #9832 by Vrishank Bhardwaj. - Feature
dummy.DummyClassifier
anddummy.DummyRegressor
can now be scored without supplying test samples. #11951 by Rüdiger Busche.
sklearn.ensemble
¶
- Feature
ensemble.BaggingRegressor
andensemble.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. #9707 by Jimmy Wan. - Feature
ensemble.GradientBoostingClassifier
andensemble.GradientBoostingRegressor
now support early stopping vian_iter_no_change
,validation_fraction
andtol
. #7071 by Raghav RV - Feature Added
named_estimators_
parameter inensemble.VotingClassifier
to access fitted estimators. #9157 by Herilalaina Rakotoarison. - Fix Fixed a bug when fitting
ensemble.GradientBoostingClassifier
orensemble.GradientBoostingRegressor
withwarm_start=True
which previously raised a segmentation fault due to a non-conversion of CSC matrix into CSR format expected bydecision_function
. Similarly, Fortran-ordered arrays are converted to C-ordered arrays in the dense case. #9991 by Guillaume Lemaitre. - Fix Fixed a bug in
ensemble.GradientBoostingRegressor
andensemble.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. #11176 by Gil Forsyth. - API Change The default value of the
n_estimators
parameter ofensemble.RandomForestClassifier
,ensemble.RandomForestRegressor
,ensemble.ExtraTreesClassifier
,ensemble.ExtraTreesRegressor
, andensemble.RandomTreesEmbedding
will change from 10 in version 0.20 to 100 in 0.22. A FutureWarning is raised when the default value is used. #11542 by Anna Ayzenshtat. - API Change Classes derived from
ensemble.BaseBagging
. The attributeestimators_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. #9524 by Guillaume Lemaitre. - Fix
ensemble.BaseBagging
where one could not deterministically reproducefit
result using the object attributes whenrandom_state
is set. #9723 by Guillaume Lemaitre.
sklearn.feature_extraction
¶
- Feature Enable the call to get_feature_names in unfitted
feature_extraction.text.CountVectorizer
initialized with a vocabulary. #10908 by Mohamed Maskani. - Enhancement
idf_
can now be set on afeature_extraction.text.TfidfTransformer
. #10899 by Sergey Melderis. - Fix Fixed a bug in
feature_extraction.image.extract_patches_2d
which would throw an exception ifmax_patches
was greater than or equal to the number of all possible patches rather than simply returning the number of possible patches. #10101 by Varun Agrawal - Fix Fixed a bug in
feature_extraction.text.CountVectorizer
,feature_extraction.text.TfidfVectorizer
,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). #9147 by Claes-Fredrik Mannby and Roman Yurchak. - Fix Fixed bug in
feature_extraction.text.TfidfVectorizer
which was ignoring the parameterdtype
. In addition,feature_extraction.text.TfidfTransformer
will preservedtype
for floating and raise a warning ifdtype
requested is integer. #10441 by Mayur Kulkarni and Guillaume Lemaitre.
sklearn.feature_selection
¶
- Feature Added select K best features functionality to
feature_selection.SelectFromModel
. #6689 by Nihar Sheth and Quazi Rahman. - Feature Added
min_features_to_select
parameter tofeature_selection.RFECV
to bound evaluated features counts. #11293 by Brent Yi. - Feature
feature_selection.RFECV
’s fit method now supports groups. #9656 by Adam Greenhall. - Fix Fixed computation of
n_features_to_compute
for edge case with tied CV scores infeature_selection.RFECV
. #9222 by Nick Hoh.
sklearn.gaussian_process
¶
- Efficiency In
gaussian_process.GaussianProcessRegressor
, methodpredict
is faster when usingreturn_std=True
in particular more when called several times in a row. #9234 by andrewww and Minghui Liu.
sklearn.impute
¶
- New module, adopting
preprocessing.Imputer
asimpute.SimpleImputer
with minor changes (see under preprocessing below). - Major Feature Added
impute.MissingIndicator
which generates a binary indicator for missing values. #8075 by Maniteja Nandana and Guillaume Lemaitre. - Feature The
impute.SimpleImputer
has a new strategy,'constant'
, to complete missing values with a fixed one, given by thefill_value
parameter. This strategy supports numeric and non-numeric data, and so does the'most_frequent'
strategy now. #11211 by Jeremie du Boisberranger.
sklearn.isotonic
¶
- Fix Fixed a bug in
isotonic.IsotonicRegression
which incorrectly combined weights when fitting a model to data involving points with identical X values. #9484 by Dallas Card
sklearn.linear_model
¶
- Feature
linear_model.SGDClassifier
,linear_model.SGDRegressor
,linear_model.PassiveAggressiveClassifier
,linear_model.PassiveAggressiveRegressor
andlinear_model.Perceptron
now exposeearly_stopping
,validation_fraction
andn_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 timen_iter_no_change
consecutive epochs fail to improve the model. #9043 by Tom Dupre la Tour. - Feature Add sample_weight parameter to the fit method of
linear_model.BayesianRidge
for weighted linear regression. #10112 by Peter St. John. - Fix Fixed a bug in
logistic.logistic_regression_path
to ensure that the returned coefficients are correct whenmulticlass='multinomial'
. Previously, some of the coefficients would override each other, leading to incorrect results inlinear_model.LogisticRegressionCV
. #11724 by Nicolas Hug. - Fix Fixed a bug in
linear_model.LogisticRegression
where when using the parametermulti_class='multinomial'
, thepredict_proba
method was returning incorrect probabilities in the case of binary outcomes. #9939 by Roger Westover. - Fix Fixed a bug in
linear_model.LogisticRegressionCV
where thescore
method always computes accuracy, not the metric given by thescoring
parameter. #10998 by Thomas Fan. - Fix Fixed a bug in
linear_model.LogisticRegressionCV
where the ‘ovr’ strategy was always used to compute cross-validation scores in the multiclass setting, even if'multinomial'
was set. #8720 by William de Vazelhes. - Fix Fixed a bug in
linear_model.OrthogonalMatchingPursuit
that was broken when settingnormalize=False
. #10071 by Alexandre Gramfort. - Fix Fixed a bug in
linear_model.ARDRegression
which caused incorrectly updated estimates for the standard deviation and the coefficients. #10153 by Jörg Döpfert. - Fix Fixed a bug in
linear_model.ARDRegression
andlinear_model.BayesianRidge
which caused NaN predictions when fitted with a constant target. #10095 by Jörg Döpfert. - Fix Fixed a bug in
linear_model.RidgeClassifierCV
where the parameterstore_cv_values
was not implemented though it was documented incv_values
as a way to set up the storage of cross-validation values for different alphas. #10297 by Mabel Villalba-Jiménez. - Fix Fixed a bug in
linear_model.ElasticNet
which caused the input to be overridden when using parametercopy_X=True
andcheck_input=False
. #10581 by Yacine Mazari. - Fix Fixed a bug in
sklearn.linear_model.Lasso
where the coefficient had wrong shape whenfit_intercept=False
. #10687 by Martin Hahn. - Fix Fixed a bug in
sklearn.linear_model.LogisticRegression
where themulti_class='multinomial'
with binary outputwith warm_start=True
#10836 by Aishwarya Srinivasan. - Fix Fixed a bug in
linear_model.RidgeCV
where using integeralphas
raised an error. #10397 by Mabel Villalba-Jiménez. - Fix Fixed condition triggering gap computation in
linear_model.Lasso
andlinear_model.ElasticNet
when working with sparse matrices. #10992 by Alexandre Gramfort. - Fix Fixed a bug in
linear_model.SGDClassifier
,linear_model.SGDRegressor
,linear_model.PassiveAggressiveClassifier
,linear_model.PassiveAggressiveRegressor
andlinear_model.Perceptron
, where the stopping criterion was stopping the algorithm before convergence. A parametern_iter_no_change
was added and set by default to 5. Previous behavior is equivalent to setting the parameter to 1. #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. #11327 by Karan Dhingra and Joel Nothman.
- API Change The default values of the
solver
andmulti_class
parameters oflinear_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. #11905 by Tom Dupre la Tour and Joel Nothman. - API Change Deprecate
positive=True
option inlinear_model.Lars
as the underlying implementation is broken. Uselinear_model.Lasso
instead. #9837 by Alexandre Gramfort. - API Change
n_iter_
may vary from previous releases inlinear_model.LogisticRegression
withsolver='lbfgs'
andlinear_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 mostmax_iter
iterations even if more were performed. #10723 by Joel Nothman.
sklearn.manifold
¶
- Efficiency Speed improvements for both ‘exact’ and ‘barnes_hut’ methods in
manifold.TSNE
. #10593 and #10610 by Tom Dupre la Tour. - Feature Support sparse input in
manifold.Isomap.fit
. #8554 by Leland McInnes. - Feature
manifold.t_sne.trustworthiness
accepts metrics other than Euclidean. #9775 by William de Vazelhes. - Fix Fixed a bug in
manifold.spectral_embedding
where the normalization of the spectrum was using a division instead of a multiplication. #8129 by Jan Margeta, Guillaume Lemaitre, and Devansh D.. - API Change Feature Deprecate
precomputed
parameter in functionmanifold.t_sne.trustworthiness
. Instead, the new parametermetric
should be used with any compatible metric including ‘precomputed’, in which case the input matrixX
should be a matrix of pairwise distances or squared distances. #9775 by William de Vazelhes. - API Change Deprecate
precomputed
parameter in functionmanifold.t_sne.trustworthiness
. Instead, the new parametermetric
should be used with any compatible metric including ‘precomputed’, in which case the input matrixX
should be a matrix of pairwise distances or squared distances. #9775 by William de Vazelhes.
sklearn.metrics
¶
- Major Feature Added the
metrics.davies_bouldin_score
metric for evaluation of clustering models without a ground truth. #10827 by Luis Osa. - Major Feature Added the
metrics.balanced_accuracy_score
metric and a corresponding'balanced_accuracy'
scorer for binary and multiclass classification. #8066 by @xyguo and Aman Dalmia, and #10587 by Joel Nothman. - Feature Partial AUC is available via
max_fpr
parameter inmetrics.roc_auc_score
. #3840 by Alexander Niederbühl. - Feature A scorer based on
metrics.brier_score_loss
is also available. #9521 by Hanmin Qin. - Feature Added control over the normalization in
metrics.normalized_mutual_info_score
andmetrics.adjusted_mutual_info_score
via theaverage_method
parameter. In version 0.22, the default normalizer for each will become the arithmetic mean of the entropies of each clustering. #11124 by Arya McCarthy. - Feature Added
output_dict
parameter inmetrics.classification_report
to return classification statistics as dictionary. #11160 by Dan Barkhorn. - Feature
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. #11679 by Alexander Pacha. - Feature
metrics.average_precision_score
now supports binaryy_true
other than{0, 1}
or{-1, 1}
throughpos_label
parameter. #9980 by Hanmin Qin. - Feature
metrics.label_ranking_average_precision_score
now supportssample_weight
. #10845 by Jose Perez-Parras Toledano. - Feature Add
dense_output
parameter tometrics.pairwise.linear_kernel
. When False and both inputs are sparse, will return a sparse matrix. #10999 by Taylor G Smith. - Efficiency
metrics.silhouette_score
andmetrics.silhouette_samples
are more memory efficient and run faster. This avoids some reported freezes and MemoryErrors. #11135 by Joel Nothman. - Fix Fixed a bug in
metrics.precision_recall_fscore_support
when truncated range(n_labels) is passed as value for labels. #10377 by Gaurav Dhingra. - Fix Fixed a bug due to floating point error in
metrics.roc_auc_score
with non-integer sample weights. #9786 by Hanmin Qin. - Fix Fixed a bug where
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 frommetrics.roc_auc_score
#10093 by alexryndin and Hanmin Qin. - Fix Fixed a bug to avoid integer overflow. Casted product to 64 bits integer in
metrics.mutual_info_score
. #9772 by Kumar Ashutosh. - Fix Fixed a bug where
metrics.average_precision_score
will sometimes returnnan
whensample_weight
contains 0. #9980 by Hanmin Qin. - Fix Fixed a bug in
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. #9515 by Alan Liddell and Manh Dao. - API Change Deprecate
reorder
parameter inmetrics.auc
as it’s no longer required formetrics.roc_auc_score
. Moreover usingreorder=True
can hide bugs due to floating point error in the input. #9851 by Hanmin Qin. - API Change In
metrics.normalized_mutual_info_score
andmetrics.adjusted_mutual_info_score
, warn thataverage_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,metrics.normalized_mutual_info_score
uses the default ofaverage_method='geometric'
, andmetrics.adjusted_mutual_info_score
uses the default ofaverage_method='max'
to match their behaviors in version 0.19. #11124 by Arya McCarthy. - API Change The
batch_size
parameter tometrics.pairwise_distances_argmin_min
andmetrics.pairwise_distances_argmin
is deprecated to be removed in v0.22. It no longer has any effect, as batch size is determined by globalworking_memory
config. See Limiting Working Memory. #10280 by Joel Nothman and Aman Dalmia.
sklearn.mixture
¶
- Feature Added function fit_predict to
mixture.GaussianMixture
andmixture.GaussianMixture
, which is essentially equivalent to calling fit and predict. #10336 by Shu Haoran and Andrew Peng. - Fix Fixed a bug in
mixture.BaseMixture
where the reported n_iter_ was missing an iteration. It affectedmixture.GaussianMixture
andmixture.BayesianGaussianMixture
. #10740 by Erich Schubert and Guillaume Lemaitre. - Fix Fixed a bug in
mixture.BaseMixture
and its subclassesmixture.GaussianMixture
andmixture.BayesianGaussianMixture
where thelower_bound_
was not the max lower bound across all initializations (whenn_init > 1
), but just the lower bound of the last initialization. #10869 by Aurélien Géron.
sklearn.model_selection
¶
- Feature Add return_estimator parameter in
model_selection.cross_validate
to return estimators fitted on each split. #9686 by Aurélien Bellet. - Feature New
refit_time_
attribute will be stored inmodel_selection.GridSearchCV
andmodel_selection.RandomizedSearchCV
ifrefit
is set toTrue
. This will allow measuring the complete time it takes to perform hyperparameter optimization and refitting the best model on the whole dataset. #11310 by Matthias Feurer. - Feature Expose error_score parameter in
model_selection.cross_validate
,model_selection.cross_val_score
,model_selection.learning_curve
andmodel_selection.validation_curve
to control the behavior triggered when an error occurs inmodel_selection._fit_and_score
. #11576 by Samuel O. Ronsin. - Feature BaseSearchCV now has an experimental, private interface to
support customized parameter search strategies, through its
_run_search
method. See the implementations inmodel_selection.GridSearchCV
andmodel_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. #9599 by Joel Nothman - Enhancement Add improved error message in
model_selection.cross_val_score
when multiple metrics are passed inscoring
keyword. #11006 by Ming Li. - API Change The default number of cross-validation folds
cv
and the default number of splitsn_splits
in themodel_selection.KFold
-like splitters will change from 3 to 5 in 0.22 as 3-fold has a lot of variance. #11557 by Alexandre Boucaud. - API Change The default of
iid
parameter ofmodel_selection.GridSearchCV
andmodel_selection.RandomizedSearchCV
will change fromTrue
toFalse
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. #9085 by Laurent Direr and Andreas Müller. - API Change The default value of the
error_score
parameter inmodel_selection.GridSearchCV
andmodel_selection.RandomizedSearchCV
will change tonp.NaN
in version 0.22. #10677 by Kirill Zhdanovich. - API Change Changed ValueError exception raised in
model_selection.ParameterSampler
to a UserWarning for case where the class is instantiated with a greater value ofn_iter
than the total space of parameters in the parameter grid.n_iter
now acts as an upper bound on iterations. #10982 by Juliet Lawton - API Change Invalid input for
model_selection.ParameterGrid
now raises TypeError. #10928 by Solutus Immensus
sklearn.multioutput
¶
- Major Feature Added
multioutput.RegressorChain
for multi-target regression. #9257 by Kumar Ashutosh.
sklearn.naive_bayes
¶
- Major Feature Added
naive_bayes.ComplementNB
, which implements the Complement Naive Bayes classifier described in Rennie et al. (2003). #8190 by Michael A. Alcorn. - Feature Add var_smoothing parameter in
naive_bayes.GaussianNB
to give a precise control over variances calculation. #9681 by Dmitry Mottl. - Fix Fixed a bug in
naive_bayes.GaussianNB
which incorrectly raised error for prior list which summed to 1. #10005 by Gaurav Dhingra. - Fix Fixed a bug in
naive_bayes.MultinomialNB
which did not accept vector valued pseudocounts (alpha). #10346 by Tobias Madsen
sklearn.neighbors
¶
- Efficiency
neighbors.RadiusNeighborsRegressor
andneighbors.RadiusNeighborsClassifier
are now parallelized according ton_jobs
regardless ofalgorithm
. #10887 by Joël Billaud. - Efficiency
Nearest neighbors
query methods are now more memory efficient whenalgorithm='brute'
. #11136 by Joel Nothman and Aman Dalmia. - Feature Add
sample_weight
parameter to the fit method ofneighbors.KernelDensity
to enable weighting in kernel density estimation. #4394 by Samuel O. Ronsin. - Feature Novelty detection with
neighbors.LocalOutlierFactor
: Add anovelty
parameter toneighbors.LocalOutlierFactor
. Whennovelty
is set to True,neighbors.LocalOutlierFactor
can then be used for novelty detection, i.e. predict on new unseen data. Available prediction methods arepredict
,decision_function
andscore_samples
. By default,novelty
is set toFalse
, and only thefit_predict
method is avaiable. By Albert Thomas. - Fix Fixed a bug in
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. #9579 by Thomas Kober. - Fix Fixed a bug so
predict
inneighbors.RadiusNeighborsRegressor
can handle empty neighbor set when using non uniform weights. Also raises a new warning when no neighbors are found for samples. #9655 by Andreas Bjerre-Nielsen. - Fix Efficiency Fixed a bug in
KDTree
construction that results in faster construction and querying times. #11556 by Jake VanderPlas - Fix Fixed a bug in
neighbors.KDTree
andneighbors.BallTree
where pickled tree objects would change their type to the super classBinaryTree
. #11774 by Nicolas Hug.
sklearn.neural_network
¶
- Feature Add n_iter_no_change parameter in
neural_network.BaseMultilayerPerceptron
,neural_network.MLPRegressor
, andneural_network.MLPClassifier
to give control over maximum number of epochs to not meettol
improvement. #9456 by Nicholas Nadeau. - Fix Fixed a bug in
neural_network.BaseMultilayerPerceptron
,neural_network.MLPRegressor
, andneural_network.MLPClassifier
with newn_iter_no_change
parameter now at 10 from previously hardcoded 2. #9456 by Nicholas Nadeau. - Fix Fixed a bug in
neural_network.MLPRegressor
where fitting quit unexpectedly early due to local minima or fluctuations. #9456 by Nicholas Nadeau
sklearn.pipeline
¶
- Feature The
predict
method ofpipeline.Pipeline
now passes keyword arguments on to the pipeline’s last estimator, enabling the use of parameters such asreturn_std
in a pipeline with caution. #9304 by Breno Freitas. - API Change
pipeline.FeatureUnion
now supports'drop'
as a transformer to drop features. #11144 by Thomas Fan.
sklearn.preprocessing
¶
- Major Feature Expanded
preprocessing.OneHotEncoder
to allow to encode categorical string features as a numeric array using a one-hot (or dummy) encoding scheme, and addedpreprocessing.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. #9151 and #10521 by Vighnesh Birodkar and Joris Van den Bossche. - Major Feature Added
preprocessing.KBinsDiscretizer
for turning continuous features into categorical or one-hot encoded features. #7668, #9647, #10195, #10192, #11272, #11467 and #11505. by Henry Lin, Hanmin Qin, Tom Dupre la Tour and Giovanni Giuseppe Costa. - Major Feature Added
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. #10210 by Eric Chang and Maniteja Nandana, and #11520 by Nicolas Hug. - Major Feature NaN values are ignored and handled in the following
preprocessing methods:
preprocessing.MaxAbsScaler
,preprocessing.MinMaxScaler
,preprocessing.RobustScaler
,preprocessing.StandardScaler
,preprocessing.PowerTransformer
,preprocessing.QuantileTransformer
classes andpreprocessing.maxabs_scale
,preprocessing.minmax_scale
,preprocessing.robust_scale
,preprocessing.scale
,preprocessing.power_transform
,preprocessing.quantile_transform
functions respectively addressed in issues #11011, #11005, #11308, #11206, #11306, and #10437. By Lucija Gregov and Guillaume Lemaitre. - Feature
preprocessing.PolynomialFeatures
now supports sparse input. #10452 by Aman Dalmia and Joel Nothman. - Feature
preprocessing.RobustScaler
andpreprocessing.robust_scale
can be fitted using sparse matrices. #11308 by Guillaume Lemaitre. - Feature
preprocessing.OneHotEncoder
now supports the get_feature_names method to obtain the transformed feature names. #10181 by Nirvan Anjirbag and Joris Van den Bossche. - Feature A parameter
check_inverse
was added topreprocessing.FunctionTransformer
to ensure thatfunc
andinverse_func
are the inverse of each other. #9399 by Guillaume Lemaitre. - Feature The
transform
method ofsklearn.preprocessing.MultiLabelBinarizer
now ignores any unknown classes. A warning is raised stating the unknown classes classes found which are ignored. #10913 by Rodrigo Agundez. - Fix Fixed bugs in
preprocessing.LabelEncoder
which would sometimes throw errors whentransform
orinverse_transform
was called with empty arrays. #10458 by Mayur Kulkarni. - Fix Fix ValueError in
preprocessing.LabelEncoder
when usinginverse_transform
on unseen labels. #9816 by Charlie Newey. - Fix Fix bug in
preprocessing.OneHotEncoder
which discarded thedtype
when returning a sparse matrix output. #11042 by Daniel Morales. - Fix Fix
fit
andpartial_fit
inpreprocessing.StandardScaler
in the rare case whenwith_mean=False
and with_std=False which was crashing by callingfit
more than once and giving inconsistent results formean_
whether the input was a sparse or a dense matrix.mean_
will be set toNone
with both sparse and dense inputs.n_samples_seen_
will be also reported for both input types. #11235 by Guillaume Lemaitre. - API Change Deprecate
n_values
andcategorical_features
parameters andactive_features_
,feature_indices_
andn_values_
attributes ofpreprocessing.OneHotEncoder
. Then_values
parameter can be replaced with the newcategories
parameter, and the attributes with the newcategories_
attribute. Selecting the categorical features with thecategorical_features
parameter is now better supported using thecompose.ColumnTransformer
. #10521 by Joris Van den Bossche. - API Change Deprecate
preprocessing.Imputer
and move the corresponding module toimpute.SimpleImputer
. #9726 by Kumar Ashutosh. - API Change The
axis
parameter that was inpreprocessing.Imputer
is no longer present inimpute.SimpleImputer
. The behavior is equivalent toaxis=0
(impute along columns). Row-wise imputation can be performed with FunctionTransformer (e.g.,FunctionTransformer(lambda X: SimpleImputer().fit_transform(X.T).T)
). #10829 by Guillaume Lemaitre and Gilberto Olimpio. - API Change The NaN marker for the missing values has been changed
between the
preprocessing.Imputer
and theimpute.SimpleImputer
.missing_values='NaN'
should now bemissing_values=np.nan
. #11211 by Jeremie du Boisberranger. - API Change In
preprocessing.FunctionTransformer
, the default ofvalidate
will be fromTrue
toFalse
in 0.22. #10655 by Guillaume Lemaitre.
sklearn.svm
¶
- Fix Fixed a bug in
svm.SVC
where when the argumentkernel
is unicode in Python2, thepredict_proba
method was raising an unexpected TypeError given dense inputs. #10412 by Jiongyan Zhang. - API Change Deprecate
random_state
parameter insvm.OneClassSVM
as the underlying implementation is not random. #9497 by Albert Thomas. - API Change The default value of
gamma
parameter ofsvm.SVC
,NuSVC
,SVR
,NuSVR
,OneClassSVM
will change from'auto'
to'scale'
in version 0.22 to account better for unscaled features. #8361 by Gaurav Dhingra and Ting Neo.
sklearn.tree
¶
- Enhancement Although private (and hence not assured API stability),
tree._criterion.ClassificationCriterion
andtree._criterion.RegressionCriterion
may now be cimported and extended. #10325 by Camil Staps. - Fix Fixed a bug in
tree.BaseDecisionTree
with splitter=”best” where split threshold could become infinite when values in X were near infinite. #10536 by Jonathan Ohayon. - 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. #11464 by John Stott.
sklearn.utils
¶
- Feature
utils.check_array
andutils.check_X_y
now haveaccept_large_sparse
to control whether scipy.sparse matrices with 64-bit indices should be rejected. #11327 by Karan Dhingra and Joel Nothman. - Efficiency Fix Avoid copying the data in
utils.check_array
when the input data is a memmap (andcopy=False
). #10663 by Arthur Mensch and Loïc Estève. - API Change
utils.check_array
yield aFutureWarning
indicating that arrays of bytes/strings will be interpreted as decimal numbers beginning in version 0.22. #10229 by Ryan Lee
Multiple modules¶
- Feature API Change More consistent outlier detection API:
Add a
score_samples
method insvm.OneClassSVM
,ensemble.IsolationForest
,neighbors.LocalOutlierFactor
,covariance.EllipticEnvelope
. It allows to access raw score functions from original papers. A newoffset_
parameter allows to linkscore_samples
anddecision_function
methods. Thecontamination
parameter ofensemble.IsolationForest
andneighbors.LocalOutlierFactor
decision_function
methods is used to define thisoffset_
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. Incovariance.EllipticEnvelope
decision_function
method, theraw_values
parameter is deprecated as the shifted Mahalanobis distance will be always returned in 0.22. #9015 by Nicolas Goix. - Feature API Change A
behaviour
parameter has been introduced inensemble.IsolationForest
to ensure backward compatibility. In the old behaviour, thedecision_function
is independent of thecontamination
parameter. A threshold attribute depending on thecontamination
parameter is thus used. In the new behaviour thedecision_function
is dependent on thecontamination
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. #11553 by Nicolas Goix. - API Change Added convergence warning to
svm.LinearSVC
andlinear_model.LogisticRegression
whenverbose
is set to 0. #10881 by Alexandre Sevin. - API Change Changed warning type from
UserWarning
toexceptions.ConvergenceWarning
for failing convergence inlinear_model.logistic_regression_path
,linear_model.RANSACRegressor
,linear_model.ridge_regression
,gaussian_process.GaussianProcessRegressor
,gaussian_process.GaussianProcessClassifier
,decomposition.fastica
,cross_decomposition.PLSCanonical
,cluster.AffinityPropagation
, andcluster.Birch
. #10306 by Jonathan Siebert.
Miscellaneous¶
- Major Feature A new configuration parameter,
working_memory
was added to control memory consumption limits in chunked operations, such as the newmetrics.pairwise_distances_chunked
. See Limiting Working Memory. #10280 by Joel Nothman and Aman Dalmia. - Feature The version of
joblib
bundled with Scikit-learn is now 0.12. This uses a new default multiprocessing implementation, named loky. While this may incur some memory and communication overhead, it should provide greater cross-platform stability than relying on Python standard library multiprocessing. #11741 by the Joblib developers, especially Thomas Moreau and Olivier Grisel. - Feature An environment variable to use the site joblib instead of the
vendored one was added (Environment variables). The main API of joblib
is now exposed in
sklearn.utils
. #11166 by Gael Varoquaux. - Feature Add almost complete PyPy 3 support. Known unsupported
functionalities are
datasets.load_svmlight_file
,feature_extraction.FeatureHasher
andfeature_extraction.text.HashingVectorizer
. For running on PyPy, PyPy3-v5.10+, Numpy 1.14.0+, and scipy 1.1.0+ are required. #11010 by Ronan Lamy and Roman Yurchak. - Feature A utility method
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. #11596 by Alexandre Boucaud - Fix Fixed a bug when setting parameters on meta-estimator, involving both a wrapped estimator and its parameter. #9999 by Marcus Voss and Joel Nothman.
- Fix Fixed a bug where calling
sklearn.base.clone
was not thread safe and could result in a “pop from empty list” error. #9569 by Andreas Müller. - API Change The default value of
n_jobs
is changed from1
toNone
in all related functions and classes.n_jobs=None
meansunset
. It will generally be interpreted asn_jobs=1
, unless the currentjoblib.Parallel
backend context specifies otherwise (See Glossary for additional information). Note that this change happens immediately (i.e., without a deprecation cycle). #11741 by Olivier Grisel. - Fix Fixed a bug in validation helpers where passing a Dask DataFrame results in an error. #12462 by Zachariah Miller
Changes to estimator checks¶
These changes mostly affect library developers.
- Checks for transformers now apply if the estimator implements
transform, regardless of whether it inherits from
sklearn.base.TransformerMixin
. #10474 by Joel Nothman. - Classifiers are now checked for consistency between decision_function and categorical predictions. #10500 by Narine Kokhlikyan.
- Allow tests in
utils.estimator_checks.check_estimator
to test functions that accept pairwise data. #9701 by Kyle Johnson - Allow
utils.estimator_checks.check_estimator
to check that there is no private settings apart from parameters during estimator initialization. #9378 by Herilalaina Rakotoarison - The set of checks in
utils.estimator_checks.check_estimator
now includes acheck_set_params
test which checks thatset_params
is equivalent to passing parameters in__init__
and warns if it encounters parameter validation. #7738 by Alvin Chiang - Add invariance tests for clustering metrics. #8102 by Ankita Sinha and Guillaume Lemaitre.
- Add
check_methods_subset_invariance
tocheck_estimator
, which checks that estimator methods are invariant if applied to a data subset. #10428 by Jonathan Ohayon - Add tests in
utils.estimator_checks.check_estimator
to check that an estimator can handle read-only memmap input data. #10663 by Arthur Mensch and Loïc Estève. check_sample_weights_pandas_series
now uses 8 rather than 6 samples to accommodate for the default number of clusters incluster.KMeans
. #10933 by Johannes Hansen.- Estimators are now checked for whether
sample_weight=None
equates tosample_weight=np.ones(...)
. #11558 by Sergul Aydore.
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, MarsGuy, Martin Gubri, martin-hahn, martin-kokos, mathurinm, Matthias Feurer, Max Copeland, Mayur Kulkarni, Meghann Agarwal, Melanie Goetz, Michael A. Alcorn, Minghui Liu, Ming Li, Minh Le, Mohamed Ali Jamaoui, Mohamed Maskani, Mohammad Shahebaz, Muayyad Alsadi, Nabarun Pal, Nagarjuna Kumar, Naoya Kanai, Narendran Santhanam, NarineK, Nathaniel Saul, Nathan Suh, Nicholas Nadeau, P.Eng., AVS, Nick Hoh, Nicolas Goix, Nicolas Hug, Nicolau Werneck, nielsenmarkus11, Nihar Sheth, Nikita Titov, Nilesh Kevlani, Nirvan Anjirbag, notmatthancock, nzw, Oleksandr Pavlyk, oliblum90, Oliver Rausch, Olivier Grisel, Oren Milman, Osaid Rehman Nasir, pasbi, Patrick Fernandes, Patrick Olden, Paul Paczuski, Pedro Morales, Peter, Peter St. John, pierreablin, pietruh, Pinaki Nath Chowdhury, Piotr Szymański, Pradeep Reddy Raamana, Pravar D Mahajan, pravarmahajan, QingYing Chen, Raghav RV, Rajendra arora, RAKOTOARISON Herilalaina, Rameshwar Bhaskaran, RankyLau, Rasul Kerimov, Reiichiro Nakano, Rob, Roman Kosobrodov, Roman Yurchak, Ronan Lamy, rragundez, Rüdiger Busche, Ryan, Sachin Kelkar, Sagnik Bhattacharya, Sailesh Choyal, Sam Radhakrishnan, Sam Steingold, Samuel Bell, Samuel O. Ronsin, Saqib Nizam Shamsi, SATISH J, Saurabh Gupta, Scott Gigante, Sebastian Flennerhag, Sebastian Raschka, Sebastien Dubois, Sébastien Lerique, Sebastin Santy, Sergey Feldman, Sergey Melderis, Sergul Aydore, Shahebaz, Shalil Awaley, Shangwu Yao, Sharad Vijalapuram, Sharan Yalburgi, shenhanc78, Shivam Rastogi, Shu Haoran, siftikha, Sinclert Pérez, SolutusImmensus, Somya Anand, srajan paliwal, Sriharsha Hatwar, Sri Krishna, Stefan van der Walt, Stephen McDowell, Steven Brown, syonekura, Taehoon Lee, Takanori Hayashi, tarcusx, Taylor G Smith, theriley106, Thomas, Thomas Fan, Thomas Heavey, Tobias Madsen, tobycheese, Tom Augspurger, Tom Dupré la Tour, Tommy, Trevor Stephens, Trishnendu Ghorai, Tulio Casagrande, twosigmajab, Umar Farouk Umar, Urvang Patel, Utkarsh Upadhyay, Vadim Markovtsev, Varun Agrawal, Vathsala Achar, Vilhelm von Ehrenheim, Vinayak Mehta, Vinit, Vinod Kumar L, Viraj Mavani, Viraj Navkal, Vivek Kumar, Vlad Niculae, vqean3, Vrishank Bhardwaj, vufg, wallygauze, Warut Vijitbenjaronk, wdevazelhes, Wenhao Zhang, Wes Barnett, Will, William de Vazelhes, Will Rosenfeld, Xin Xiong, Yiming (Paul) Li, ymazari, Yufeng, Zach Griffith, Zé Vinícius, Zhenqing Hu, Zhiqing Xiao, Zijie (ZJ) Poh