Figure 2. Scatter plots of the first and second PC scores, u_1i and u_2i, attributed to genes of the first synthetic data set.

Open grey circles represent the 990 genes not associated with the differential gene expression between the two classes, whereas the red open circles correspond to the 10 genes associated with the differential gene expression between the two classes. Blue crosses are those selected by PCA-based unsupervised FE. s = 1: top left, s = 1.5: middle and s = 2:right.