Hierarchical Clustering and k -means for Alizadeh-V2. We display the red and green plots for (a) the hierarchical clustering and (b) the k-means for the data set Alizadeh-V2. Columns correspond to genes and rows correspond to cancer samples. The samples are labeled according to one of three classes: diffuse large B-cell lymphoma (DLBCL), follicular lymphoma (FL) and chronic lymphocytic leukemia (CLL). In the case of k-means, the number of clusters was set at three. Likewise, for hierarchical clustering, the tree was cut so as to return three clusters, corresponding to the red, light blue and black sub-trees.