Heatmap of the metagene expression profiles matrix. The metagene expression profile matrix was obtained from the factorization that achieved the lowest approximation error across 200 random runs of the Brunet et al.'s algorithm on the Golub dataset. Each column corresponds to a samples. The top colored row shows the phenotypic class to which each sample belongs. Columns were scaled to sum to one and ordered by clusters, which are highlighted on the second row by colours that map them with their associated metagene.