sklearn.decomposition.dict_learning_online

sklearn.decomposition.dict_learning_online(X, n_components=2, alpha=1, n_iter=100, return_code=True, dict_init=None, callback=None, batch_size=3, verbose=False, shuffle=True, n_jobs=None, method=’lars’, iter_offset=0, random_state=None, return_inner_stats=False, inner_stats=None, return_n_iter=False, positive_dict=False, positive_code=False) [source]

Solves a dictionary learning matrix factorization problem online.

Finds the best dictionary and the corresponding sparse code for approximating the data matrix X by solving:

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

where V is the dictionary and U is the sparse code. This is accomplished by repeatedly iterating over mini-batches by slicing the input data.

Read more in the User Guide.

Parameters:

X : array of shape (n_samples, n_features) Data matrix. n_components : int, Number of dictionary atoms to extract. alpha : float, Sparsity controlling parameter. n_iter : int, Number of iterations to perform. return_code : boolean, Whether to also return the code U or just the dictionary V. dict_init : array of shape (n_components, n_features), Initial value for the dictionary for warm restart scenarios. callback : callable or None, optional (default: None) callable that gets invoked every five iterations batch_size : int, The number of samples to take in each batch. verbose : bool, optional (default: False) To control the verbosity of the procedure. shuffle : boolean, Whether to shuffle the data before splitting it in batches. n_jobs : int or None, optional (default=None) Number of parallel jobs to run. None means 1 unless in a joblib.parallel_backend context. -1 means using all processors. See Glossary for more details. method : {‘lars’, ‘cd’} lars: uses the least angle regression method to solve the lasso problem (linear_model.lars_path) cd: uses the coordinate descent method to compute the Lasso solution (linear_model.Lasso). Lars will be faster if the estimated components are sparse. iter_offset : int, default 0 Number of previous iterations completed on the dictionary used for initialization. random_state : int, RandomState instance or None, optional (default=None) If int, random_state is the seed used by the random number generator; If RandomState instance, random_state is the random number generator; If None, the random number generator is the RandomState instance used by np.random. return_inner_stats : boolean, optional Return the inner statistics A (dictionary covariance) and B (data approximation). Useful to restart the algorithm in an online setting. If return_inner_stats is True, return_code is ignored inner_stats : tuple of (A, B) ndarrays Inner sufficient statistics that are kept by the algorithm. Passing them at initialization is useful in online settings, to avoid loosing the history of the evolution. A (n_components, n_components) is the dictionary covariance matrix. B (n_features, n_components) is the data approximation matrix return_n_iter : bool Whether or not to return the number of iterations. positive_dict : bool Whether to enforce positivity when finding the dictionary. New in version 0.20. positive_code : bool Whether to enforce positivity when finding the code. New in version 0.20.

Returns:

code : array of shape (n_samples, n_components), the sparse code (only returned if return_code=True) dictionary : array of shape (n_components, n_features), the solutions to the dictionary learning problem n_iter : int Number of iterations run. Returned only if return_n_iter is set to True.

See also

dict_learning, DictionaryLearning, MiniBatchDictionaryLearning, SparsePCA, MiniBatchSparsePCA