sklearn.pipeline.FeatureUnion¶

class sklearn.pipeline.FeatureUnion(transformer_list, *, n_jobs=None, transformer_weights=None, verbose=False)[source]¶

Concatenates results of multiple transformer objects.

This estimator applies a list of transformer objects in parallel to the input data, then concatenates the results. This is useful to combine several feature extraction mechanisms into a single transformer.

Parameters of the transformers may be set using its name and the parameter name separated by a ‘__’. A transformer may be replaced entirely by setting the parameter with its name to another transformer, or removed by setting to ‘drop’.

Read more in the User Guide.

New in version 0.13.

Parameters

transformer_listlist of (string, transformer) tuples

List of transformer objects to be applied to the data. The first half of each tuple is the name of the transformer. The tranformer can be ‘drop’ for it to be ignored.

Changed in version 0.22: Deprecated None as a transformer in favor of ‘drop’.

n_jobsint, default=None

Number of jobs to run in parallel. None means 1 unless in a joblib.parallel_backend context. -1 means using all processors. See Glossary for more details.

Changed in version v0.20: n_jobs default changed from 1 to None

transformer_weightsdict, default=None

Multiplicative weights for features per transformer. Keys are transformer names, values the weights. Raises ValueError if key not present in transformer_list.

verbosebool, default=False

If True, the time elapsed while fitting each transformer will be printed as it is completed.

Attributes

n_features_in_

See also

make_union

Convenience function for simplified feature union construction.

Examples

>>> from sklearn.pipeline import FeatureUnion
>>> from sklearn.decomposition import PCA, TruncatedSVD
>>> union = FeatureUnion([("pca", PCA(n_components=1)),
...                       ("svd", TruncatedSVD(n_components=2))])
>>> X = [[0., 1., 3], [2., 2., 5]]
>>> union.fit_transform(X)
array([[ 1.5       ,  3.0...,  0.8...],
       [-1.5       ,  5.7..., -0.4...]])

Methods

fit(X[, y])	Fit all transformers using X.
fit_transform(X[, y])	Fit all transformers, transform the data and concatenate results.
get_feature_names()	Get feature names from all transformers.
get_params([deep])	Get parameters for this estimator.
set_params(**kwargs)	Set the parameters of this estimator.
transform(X)	Transform X separately by each transformer, concatenate results.

fit(X, y=None, **fit_params)[source]¶

Fit all transformers using X.

Parameters

Xiterable or array-like, depending on transformers

Input data, used to fit transformers.

yarray-like of shape (n_samples, n_outputs), default=None

Targets for supervised learning.

Returns

selfFeatureUnion

This estimator

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

Fit all transformers, transform the data and concatenate results.

Parameters

Xiterable or array-like, depending on transformers

Input data to be transformed.

yarray-like of shape (n_samples, n_outputs), default=None

Targets for supervised learning.

Returns

X_tarray-like or sparse matrix of shape (n_samples, sum_n_components)

hstack of results of transformers. sum_n_components is the sum of n_components (output dimension) over transformers.

get_feature_names()[source]¶

Get feature names from all transformers.

Returns

feature_nameslist of strings

Names of the features produced by transform.

get_params(deep=True)[source]¶

Get parameters for this estimator.

Returns the parameters given in the constructor as well as the estimators contained within the transformer_list of the FeatureUnion.

Parameters

deepbool, default=True

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

Returns

paramsmapping of string to any

Parameter names mapped to their values.

set_params(**kwargs)[source]¶

Set the parameters of this estimator.

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

Returns

self

transform(X)[source]¶

Transform X separately by each transformer, concatenate results.

Parameters

Xiterable or array-like, depending on transformers

Input data to be transformed.

Returns

X_tarray-like or sparse matrix of shape (n_samples, sum_n_components)

hstack of results of transformers. sum_n_components is the sum of n_components (output dimension) over transformers.

Examples using sklearn.pipeline.FeatureUnion¶