8.5.3. sklearn.decomposition.ProjectedGradientNMF¶
- class sklearn.decomposition.ProjectedGradientNMF(n_components=None, init='nndsvdar', sparseness=None, beta=1, eta=0.1, tol=0.0001, max_iter=200, nls_max_iter=2000)¶
Non-Negative matrix factorization by Projected Gradient (NMF)
Parameters : X: {array-like, sparse matrix}, shape = [n_samples, n_features] :
Data the model will be fit to.
n_components: int or None :
Number of components, if n_components is not set all components are kept
init: ‘nndsvd’ | ‘nndsvda’ | ‘nndsvdar’ | int | RandomState :
Method used to initialize the procedure. Default: ‘nndsvdar’ Valid options:
'nndsvd': Nonnegative Double Singular Value Decomposition (NNDSVD) initialization (better for sparseness) 'nndsvda': NNDSVD with zeros filled with the average of X (better when sparsity is not desired) 'nndsvdar': NNDSVD with zeros filled with small random values (generally faster, less accurate alternative to NNDSVDa for when sparsity is not desired) int seed or RandomState: non-negative random matrices
sparseness: ‘data’ | ‘components’ | None, default: None :
Where to enforce sparsity in the model.
beta: double, default: 1 :
Degree of sparseness, if sparseness is not None. Larger values mean more sparseness.
eta: double, default: 0.1 :
Degree of correctness to mantain, if sparsity is not None. Smaller values mean larger error.
tol: double, default: 1e-4 :
Tolerance value used in stopping conditions.
max_iter: int, default: 200 :
Number of iterations to compute.
nls_max_iter: int, default: 2000 :
Number of iterations in NLS subproblem.
Notes
This implements
C.-J. Lin. Projected gradient methods for non-negative matrix factorization. Neural Computation, 19(2007), 2756-2779. http://www.csie.ntu.edu.tw/~cjlin/nmf/
P. Hoyer. Non-negative Matrix Factorization with Sparseness Constraints. Journal of Machine Learning Research 2004.
NNDSVD is introduced in
C. Boutsidis, E. Gallopoulos: SVD based initialization: A head start for nonnegative matrix factorization - Pattern Recognition, 2008 http://www.cs.rpi.edu/~boutsc/files/nndsvd.pdf
Examples
>>> import numpy as np >>> X = np.array([[1,1], [2, 1], [3, 1.2], [4, 1], [5, 0.8], [6, 1]]) >>> from sklearn.decomposition import ProjectedGradientNMF >>> model = ProjectedGradientNMF(n_components=2, init=0) >>> model.fit(X) ProjectedGradientNMF(beta=1, eta=0.1, init=0, max_iter=200, n_components=2, nls_max_iter=2000, sparseness=None, tol=0.0001) >>> model.components_ array([[ 0.77032744, 0.11118662], [ 0.38526873, 0.38228063]]) >>> model.reconstruction_err_ 0.00746... >>> model = ProjectedGradientNMF(n_components=2, init=0, ... sparseness='components') >>> model.fit(X) ProjectedGradientNMF(beta=1, eta=0.1, init=0, max_iter=200, n_components=2, nls_max_iter=2000, sparseness='components', tol=0.0001) >>> model.components_ array([[ 1.67481991, 0.29614922], [-0. , 0.4681982 ]]) >>> model.reconstruction_err_ 0.513...
Attributes
components_ array, [n_components, n_features] Non-negative components of the data reconstruction_err_ number Frobenius norm of the matrix difference between the training data and the reconstructed data from the fit produced by the model. || X - WH ||_2 Not computed for sparse input matrices because it is too expensive in terms of memory. Methods
fit(X[, y]) Learn a NMF model for the data X. fit_transform(X[, y]) Learn a NMF model for the data X and returns the transformed data. set_params(**params) Set the parameters of the estimator. transform(X) Transform the data X according to the fitted NMF model - __init__(n_components=None, init='nndsvdar', sparseness=None, beta=1, eta=0.1, tol=0.0001, max_iter=200, nls_max_iter=2000)¶
- fit(X, y=None, **params)¶
Learn a NMF model for the data X.
Parameters : X: {array-like, sparse matrix}, shape = [n_samples, n_features] :
Data matrix to be decomposed
Returns : self :
- fit_transform(X, y=None)¶
Learn a NMF model for the data X and returns the transformed data.
This is more efficient than calling fit followed by transform.
Parameters : X: {array-like, sparse matrix}, shape = [n_samples, n_features] :
Data matrix to be decomposed
Returns : data: array, [n_samples, n_components] :
Transformed data
- set_params(**params)¶
Set the parameters of the estimator.
The method works on simple estimators as well as on nested objects (such as pipelines). The former have parameters of the form <component>__<parameter> so that it’s possible to update each component of a nested object.
Returns : self :
- transform(X)¶
Transform the data X according to the fitted NMF model
Parameters : X: {array-like, sparse matrix}, shape = [n_samples, n_features] :
Data matrix to be transformed by the model
Returns : data: array, [n_samples, n_components] :
Transformed data