`sklearn.ensemble`.VotingClassifier¶

class sklearn.ensemble.VotingClassifier(estimators, *, voting='hard', weights=None, n_jobs=None, flatten_transform=True, verbose=False)[source]¶

Soft Voting/Majority Rule classifier for unfitted estimators.

See also

VotingRegressor: Prediction voting regressor.

Examples

>>> import numpy as np
>>> from sklearn.linear_model import LogisticRegression
>>> from sklearn.naive_bayes import GaussianNB
>>> from sklearn.ensemble import RandomForestClassifier, VotingClassifier
>>> clf1 = LogisticRegression(multi_class='multinomial', random_state=1)
>>> clf2 = RandomForestClassifier(n_estimators=50, random_state=1)
>>> clf3 = GaussianNB()
>>> X = np.array([[-1, -1], [-2, -1], [-3, -2], [1, 1], [2, 1], [3, 2]])
>>> y = np.array([1, 1, 1, 2, 2, 2])
>>> eclf1 = VotingClassifier(estimators=[
...         ('lr', clf1), ('rf', clf2), ('gnb', clf3)], voting='hard')
>>> eclf1 = eclf1.fit(X, y)
>>> print(eclf1.predict(X))
[1 1 1 2 2 2]
>>> np.array_equal(eclf1.named_estimators_.lr.predict(X),
...                eclf1.named_estimators_['lr'].predict(X))
True
>>> eclf2 = VotingClassifier(estimators=[
...         ('lr', clf1), ('rf', clf2), ('gnb', clf3)],
...         voting='soft')
>>> eclf2 = eclf2.fit(X, y)
>>> print(eclf2.predict(X))
[1 1 1 2 2 2]

To drop an estimator, set_params can be used to remove it. Here we dropped one of the estimators, resulting in 2 fitted estimators:

>>> eclf2 = eclf2.set_params(lr='drop')
>>> eclf2 = eclf2.fit(X, y)
>>> len(eclf2.estimators_)
2

Setting flatten_transform=True with voting='soft' flattens output shape of transform:

>>> eclf3 = VotingClassifier(estimators=[
...        ('lr', clf1), ('rf', clf2), ('gnb', clf3)],
...        voting='soft', weights=[2,1,1],
...        flatten_transform=True)
>>> eclf3 = eclf3.fit(X, y)
>>> print(eclf3.predict(X))
[1 1 1 2 2 2]
>>> print(eclf3.transform(X).shape)
(6, 6)

Methods

`fit`(X, y[, sample_weight])	Fit the estimators.
`fit_transform`(X[, y])	Return class labels or probabilities for each estimator.
`get_feature_names_out`([input_features])	Get output feature names for transformation.
`get_params`([deep])	Get the parameters of an estimator from the ensemble.
`predict`(X)	Predict class labels for X.
`predict_proba`(X)	Compute probabilities of possible outcomes for samples in X.
`score`(X, y[, sample_weight])	Return the mean accuracy on the given test data and labels.
`set_params`(**params)	Set the parameters of an estimator from the ensemble.
`transform`(X)	Return class labels or probabilities for X for each estimator.

fit(X, y, sample_weight=None)[source]¶

Fit the estimators.

Parameters:

X{array-like, sparse matrix} of shape (n_samples, n_features): Training vectors, where n_samples is the number of samples and n_features is the number of features.
yarray-like of shape (n_samples,): Target values.
sample_weightarray-like of shape (n_samples,), default=None: Sample weights. If None, then samples are equally weighted. Note that this is supported only if all underlying estimators support sample weights.

New in version 0.18.

Returns:

selfobject: Returns the instance itself.

fit_transform(X, y=None, **fit_params)[source]¶

Return class labels or probabilities for each estimator.

Return predictions for X for each estimator.

Parameters:

X{array-like, sparse matrix, dataframe} of shape (n_samples, n_features): Input samples.
yndarray of shape (n_samples,), default=None: Target values (None for unsupervised transformations).
**fit_paramsdict: Additional fit parameters.

Returns:

X_newndarray array of shape (n_samples, n_features_new): Transformed array.

get_feature_names_out(input_features=None)[source]¶

Get output feature names for transformation.

Parameters:

input_featuresarray-like of str or None, default=None: Not used, present here for API consistency by convention.

Returns:

feature_names_outndarray of str objects: Transformed feature names.

get_params(deep=True)[source]¶

Get the parameters of an estimator from the ensemble.

Returns the parameters given in the constructor as well as the estimators contained within the estimators parameter.

Parameters:

deepbool, default=True: Setting it to True gets the various estimators and the parameters of the estimators as well.

Returns:

paramsdict: Parameter and estimator names mapped to their values or parameter names mapped to their values.

property n_features_in_¶: Number of features seen during fit.

property named_estimators¶

Dictionary to access any fitted sub-estimators by name.

Returns:

Bunch

predict(X)[source]¶

Predict class labels for X.

Parameters:

X{array-like, sparse matrix} of shape (n_samples, n_features): The input samples.

Returns:

majarray-like of shape (n_samples,): Predicted class labels.

predict_proba(X)[source]¶

Compute probabilities of possible outcomes for samples in X.

Parameters:

X{array-like, sparse matrix} of shape (n_samples, n_features): The input samples.

Returns:

avgarray-like of shape (n_samples, n_classes): Weighted average probability for each class per sample.

score(X, y, sample_weight=None)[source]¶

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

In multi-label classification, this is the subset accuracy which is a harsh metric since you require for each sample that each label set be correctly predicted.

Parameters:

Xarray-like of shape (n_samples, n_features): Test samples.
yarray-like of shape (n_samples,) or (n_samples, n_outputs): True labels for X.
sample_weightarray-like of shape (n_samples,), default=None: Sample weights.

Returns:

scorefloat: Mean accuracy of self.predict(X) wrt. y.

set_params(**params)[source]¶

Set the parameters of an estimator from the ensemble.

Valid parameter keys can be listed with get_params(). Note that you can directly set the parameters of the estimators contained in estimators.

Parameters:

**paramskeyword arguments: Specific parameters using e.g. set_params(parameter_name=new_value). In addition, to setting the parameters of the estimator, the individual estimator of the estimators can also be set, or can be removed by setting them to ‘drop’.

Returns:

selfobject: Estimator instance.

transform(X)[source]¶

Return class labels or probabilities for X for each estimator.

Parameters:

X{array-like, sparse matrix} of shape (n_samples, n_features): Training vectors, where n_samples is the number of samples and n_features is the number of features.

Returns:

probabilities_or_labels

If voting='soft' and flatten_transform=True:: returns ndarray of shape (n_samples, n_classifiers * n_classes), being class probabilities calculated by each classifier.
If voting='soft' and `flatten_transform=False:: ndarray of shape (n_classifiers, n_samples, n_classes)
If voting='hard':: ndarray of shape (n_samples, n_classifiers), being class labels predicted by each classifier.

Examples using `sklearn.ensemble.VotingClassifier`¶

Plot class probabilities calculated by the VotingClassifier

Plot the decision boundaries of a VotingClassifier

sklearn.ensemble.VotingClassifier¶

Examples using sklearn.ensemble.VotingClassifier¶

`sklearn.ensemble`.VotingClassifier¶

Examples using `sklearn.ensemble.VotingClassifier`¶