Correspondence analysis is mainly used for detecting the changes of codon RSCU values in genes [39] . It is an effective multivariate statistical method of studying the internal relation between the variables and samples, and it is successfully applied to the study of codon. In correspondence analysis, all genes in samples are distributed in a 59-dimensional (59 justice codons, in addition to the stop codon, Met, and Trp) vector space, each gene is described with 59 (f' 1 , f' 2, ..., f' 59 ) variables, the results can be applied for finding out the major factors affecting codon usage bias in genes [40, 41] . This was done using the CodonW program.