Nonnegative matrix factorization (NMF) is a technique to factorize a matrix with nonnegative values into the product of two matrices. Covariates are also allowed. Parallel computing is an option to enhance the speed and high-dimensional and large scale (and/or sparse) data are allowed. Relevant papers include: Sevinc V., Kontemeniotis N., Perdikis T. and Tsagris M. (2026). Non-negative matrix factorization using the R package nnmf