sklearn.multioutput.MultiOutputClassifier (2024)

Multi target classification.

This strategy consists of fitting one classifier per target. This is asimple strategy for extending classifiers that do not natively supportmulti-target classification.

Parameters:

estimatorestimator object

An estimator object implementing fit and predict.A predict_proba method will be exposed only if estimator implementsit.

n_jobsint or None, optional (default=None)

The number of jobs to run in parallel.fit, predict and partial_fit (if supportedby the passed estimator) will be parallelized for each target.

When individual estimators are fast to train or predict,using n_jobs > 1 can result in slower performance dueto the parallelism overhead.

None means 1 unless in a joblib.parallel_backend context.-1 means using all available processes / threads.See Glossary for more details.

Changed in version 0.20: n_jobs default changed from 1 to None.

Attributes:

classes_ndarray of shape (n_classes,)

Class labels.

estimators_list of n_output estimators

Estimators used for predictions.

n_features_in_int

Number of features seen during fit. Only defined if theunderlying estimator exposes such an attribute when fit.

New in version 0.24.

feature_names_in_ndarray of shape (n_features_in_,)

Names of features seen during fit. Only defined if theunderlying estimators expose such an attribute when fit.

New in version 1.0.

Examples

>>> import numpy as np>>> from sklearn.datasets import make_multilabel_classification>>> from sklearn.multioutput import MultiOutputClassifier>>> from sklearn.linear_model import LogisticRegression>>> X, y = make_multilabel_classification(n_classes=3, random_state=0)>>> clf = MultiOutputClassifier(LogisticRegression()).fit(X, y)>>> clf.predict(X[-2:])array([[1, 1, 1], [1, 0, 1]])

Methods

fit(X, Y, sample_weight=None, **fit_params)[source]¶

Fit the model to data matrix X and targets Y.

See Also

1.12. Multiclass and multioutput algorithms - scikit-learn DocumentationBladesinger and hexblade combo - Wizard - Class Forums - D&D Beyond ForumsBladesinger 5e | A Wizard's Guide to Martial Spellcasting1.12. Multiclass and multioutput algorithms

Parameters:

X{array-like, sparse matrix} of shape (n_samples, n_features)

The input data.

Yarray-like of shape (n_samples, n_classes)

The target values.

sample_weightarray-like of shape (n_samples,), default=None

Sample weights. If None, then samples are equally weighted.Only supported if the underlying classifier supports sampleweights.

**fit_paramsdict of string -> object

Parameters passed to the estimator.fit method of each step.

New in version 0.23.

Returns:

selfobject

Returns a fitted instance.

get_metadata_routing()[source]¶

Get metadata routing of this object.

Please check User Guide on how the routingmechanism works.

New in version 1.3.

Returns:

routingMetadataRouter

A MetadataRouter encapsulatingrouting information.

get_params(deep=True)[source]¶

Get parameters for this estimator.

Parameters:

deepbool, default=True

If True, will return the parameters for this estimator andcontained subobjects that are estimators.

Returns:

paramsdict

Parameter names mapped to their values.

partial_fit(X, y, classes=None, sample_weight=None, **partial_fit_params)[source]¶

Incrementally fit a separate model for each class output.

Parameters:

X{array-like, sparse matrix} of shape (n_samples, n_features)

The input data.

y{array-like, sparse matrix} of shape (n_samples, n_outputs)

Multi-output targets.

classeslist of ndarray of shape (n_outputs,), default=None

Each array is unique classes for one output in str/int.Can be obtained via[np.unique(y[:, i]) for i in range(y.shape[1])], where yis the target matrix of the entire dataset.This argument is required for the first call to partial_fitand can be omitted in the subsequent calls.Note that y doesn’t need to contain all labels in classes.

sample_weightarray-like of shape (n_samples,), default=None

Sample weights. If None, then samples are equally weighted.Only supported if the underlying regressor supports sampleweights.

**partial_fit_paramsdict of str -> object

Parameters passed to the estimator.partial_fit method of eachsub-estimator.

Only available if enable_metadata_routing=True. See theUser Guide.

New in version 1.3.

Returns:

selfobject

Returns a fitted instance.

See Also

Bladesinger and hexblade combo - Wizard - Class Forums - D&D Beyond Forums

predict(X)[source]¶

Predict multi-output variable using model for each target variable.

Parameters:

X{array-like, sparse matrix} of shape (n_samples, n_features)

The input data.

Returns:

y{array-like, sparse matrix} of shape (n_samples, n_outputs)

Multi-output targets predicted across multiple predictors.Note: Separate models are generated for each predictor.

predict_proba(X)[source]¶

Return prediction probabilities for each class of each output.

This method will raise a ValueError if any of theestimators do not have predict_proba.

Parameters:

Xarray-like of shape (n_samples, n_features)

The input data.

Returns:

parray of shape (n_samples, n_classes), or a list of n_outputs such arrays if n_outputs > 1.

The class probabilities of the input samples. The order of theclasses corresponds to that in the attribute classes_.

Changed in version 0.19: This function now returns a list of arrays where the length ofthe list is n_outputs, and each array is (n_samples,n_classes) for that particular output.

score(X, y)[source]¶

Return the mean accuracy on the given test data and labels.

Parameters:

Xarray-like of shape (n_samples, n_features)

Test samples.

yarray-like of shape (n_samples, n_outputs)

True values for X.

Returns:

scoresfloat

Mean accuracy of predicted target versus true target.

set_fit_request(*, sample_weight: bool | None | str = '$UNCHANGED$') → MultiOutputClassifier[source]¶

Request metadata passed to the fit method.

Note that this method is only relevant ifenable_metadata_routing=True (see sklearn.set_config).Please see User Guide on how the routingmechanism works.

The options for each parameter are:

• True: metadata is requested, and passed to fit if provided. The request is ignored if metadata is not provided.

• False: metadata is not requested and the meta-estimator will not pass it to fit.

• None: metadata is not requested, and the meta-estimator will raise an error if the user provides it.

• str: metadata should be passed to the meta-estimator with this given alias instead of the original name.

The default (sklearn.utils.metadata_routing.UNCHANGED) retains theexisting request. This allows you to change the request for someparameters and not others.

New in version 1.3.

Note

This method is only relevant if this estimator is used as asub-estimator of a meta-estimator, e.g. used inside aPipeline. Otherwise it has no effect.

Parameters:

sample_weightstr, True, False, or None, default=sklearn.utils.metadata_routing.UNCHANGED

Metadata routing for sample_weight parameter in fit.

Returns:

selfobject

The updated object.

set_params(**params)[source]¶

Set the parameters of this estimator.

The method works on simple estimators as well as on nested objects(such as Pipeline). The latter haveparameters of the form <component>__<parameter> so that it’spossible to update each component of a nested object.

Parameters:

**paramsdict

Estimator parameters.

Returns:

selfestimator instance

Estimator instance.

set_partial_fit_request(*, classes: bool | None | str = '$UNCHANGED$', sample_weight: bool | None | str = '$UNCHANGED$') → MultiOutputClassifier[source]¶

Request metadata passed to the partial_fit method.

Note that this method is only relevant ifenable_metadata_routing=True (see sklearn.set_config).Please see User Guide on how the routingmechanism works.

The options for each parameter are:

• True: metadata is requested, and passed to partial_fit if provided. The request is ignored if metadata is not provided.

• False: metadata is not requested and the meta-estimator will not pass it to partial_fit.

• None: metadata is not requested, and the meta-estimator will raise an error if the user provides it.

• str: metadata should be passed to the meta-estimator with this given alias instead of the original name.

The default (sklearn.utils.metadata_routing.UNCHANGED) retains theexisting request. This allows you to change the request for someparameters and not others.

New in version 1.3.

Note

This method is only relevant if this estimator is used as asub-estimator of a meta-estimator, e.g. used inside aPipeline. Otherwise it has no effect.

Parameters:

classesstr, True, False, or None, default=sklearn.utils.metadata_routing.UNCHANGED

Metadata routing for classes parameter in partial_fit.

sample_weightstr, True, False, or None, default=sklearn.utils.metadata_routing.UNCHANGED

Metadata routing for sample_weight parameter in partial_fit.

Returns:

selfobject

The updated object.