Fig. 1
From: Profiling and analysis of chemical compounds using pointwise mutual information
Relation matrices. Co-occurrence relation matrix (CORM) is the sum of the outer products of all feature vectors k. Individual elements of co-occurrence probability relation matrix (COPRM) are calculated by dividing corresponding CORM elements by the number of feature vectors (i.e., by the size of the compound set S) |S|. Pointwise mutual information relation matrix (PMIRM) consists of PMI between all feature pairs i and j. Z-standardized pointwise mutual information relation matrix (ZPMIRM) is obtained from PMIRM by converting its elements into Z-scores