`sklearn.decomposition`.MiniBatchDictionaryLearning¶

class sklearn.decomposition.MiniBatchDictionaryLearning(n_components=None, *, alpha=1, n_iter=1000, fit_algorithm='lars', n_jobs=None, batch_size=3, shuffle=True, dict_init=None, transform_algorithm='omp', transform_n_nonzero_coefs=None, transform_alpha=None, verbose=False, split_sign=False, random_state=None, positive_code=False, positive_dict=False, transform_max_iter=1000)[source]¶

Mini-batch dictionary learning.

Finds a dictionary (a set of atoms) that performs well at sparsely encoding the fitted data.

Solves the optimization problem:

(U^*,V^*) = argmin 0.5 || X - U V ||_Fro^2 + alpha * || U ||_1,1
             (U,V)
             with || V_k ||_2 <= 1 for all  0 <= k < n_components

||.||_Fro stands for the Frobenius norm and ||.||_1,1 stands for the entry-wise matrix norm which is the sum of the absolute values of all the entries in the matrix.

See also

DictionaryLearning: Find a dictionary that sparsely encodes data.
MiniBatchSparsePCA: Mini-batch Sparse Principal Components Analysis.
SparseCoder: Find a sparse representation of data from a fixed, precomputed dictionary.
SparsePCA: Sparse Principal Components Analysis.

References

J. Mairal, F. Bach, J. Ponce, G. Sapiro, 2009: Online dictionary learning for sparse coding (https://www.di.ens.fr/sierra/pdfs/icml09.pdf)

Examples

>>> import numpy as np
>>> from sklearn.datasets import make_sparse_coded_signal
>>> from sklearn.decomposition import MiniBatchDictionaryLearning
>>> X, dictionary, code = make_sparse_coded_signal(
...     n_samples=100, n_components=15, n_features=20, n_nonzero_coefs=10,
...     random_state=42)
>>> dict_learner = MiniBatchDictionaryLearning(
...     n_components=15, transform_algorithm='lasso_lars', random_state=42,
... )
>>> X_transformed = dict_learner.fit_transform(X)

We can check the level of sparsity of X_transformed:

>>> np.mean(X_transformed == 0)
0.86...

We can compare the average squared euclidean norm of the reconstruction error of the sparse coded signal relative to the squared euclidean norm of the original signal:

>>> X_hat = X_transformed @ dict_learner.components_
>>> np.mean(np.sum((X_hat - X) ** 2, axis=1) / np.sum(X ** 2, axis=1))
0.07...

Methods

`fit`(X[, y])	Fit the model from data in X.
`fit_transform`(X[, y])	Fit to data, then transform it.
`get_params`([deep])	Get parameters for this estimator.
`partial_fit`(X[, y, iter_offset])	Update the model using the data in X as a mini-batch.
`set_params`(**params)	Set the parameters of this estimator.
`transform`(X)	Encode the data as a sparse combination of the dictionary atoms.

fit(X, y=None)[source]¶

Fit the model from data in X.

Parameters

Xarray-like of shape (n_samples, n_features): Training vector, where n_samples is the number of samples and n_features is the number of features.
yIgnored: Not used, present for API consistency by convention.

Returns

selfobject: Returns the instance itself.

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

Fit to data, then transform it.

Fits transformer to X and y with optional parameters fit_params and returns a transformed version of X.

Parameters

Xarray-like of shape (n_samples, n_features): Input samples.
yarray-like of shape (n_samples,) or (n_samples, n_outputs), 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_params(deep=True)[source]¶

Get parameters for this estimator.

Parameters

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

Returns

paramsdict: Parameter names mapped to their values.

partial_fit(X, y=None, iter_offset=None)[source]¶

Update the model using the data in X as a mini-batch.

Parameters

Xarray-like of shape (n_samples, n_features): Training vector, where n_samples is the number of samples and n_features is the number of features.
yIgnored: Not used, present for API consistency by convention.
iter_offsetint, default=None: The number of iteration on data batches that has been performed before this call to partial_fit. This is optional: if no number is passed, the memory of the object is used.

Returns

selfobject: Returns the instance itself.

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 have parameters of the form <component>__<parameter> so that it’s possible to update each component of a nested object.

Parameters

**paramsdict: Estimator parameters.

Returns

selfestimator instance: Estimator instance.

transform(X)[source]¶

Encode the data as a sparse combination of the dictionary atoms.

Coding method is determined by the object parameter transform_algorithm.

Parameters

Xndarray of shape (n_samples, n_features): Test data to be transformed, must have the same number of features as the data used to train the model.

Returns

X_newndarray of shape (n_samples, n_components): Transformed data.

Examples using `sklearn.decomposition.MiniBatchDictionaryLearning`¶

sklearn.decomposition.MiniBatchDictionaryLearning¶

Examples using sklearn.decomposition.MiniBatchDictionaryLearning¶

`sklearn.decomposition`.MiniBatchDictionaryLearning¶

Examples using `sklearn.decomposition.MiniBatchDictionaryLearning`¶