Machine Learning Algorithms

Atom extraction and dictionary learning

Dictionary learning is a technique which allows rebuilding a sample starting from a sparse dictionary of atoms (similar to principal components). In Mairal J., Bach F., Ponce J., Sapiro G., Online Dictionary Learning for Sparse Coding, Proceedings of the 29th International Conference on Machine Learning, 2009 there's a description of the same online strategy adopted by scikit-learn, which can be summarized as a double optimization problem where:

Is an input dataset and the target is to find both a dictionary D and a set of weights for each sample:

After the training process, an input vector can be computed ...