the species id in KEGG database, 'hsa' means human, 'mmu' means mouse, 'rno' means rat, etc
database_dir
the directory where the XML files and png files are located
Value
a matrix containing genes in this pathway, and their names, locations etc, which could be used in the function plot_profile as param KEGG_database
Details
This function will parse the KEGG XML (KGML) file. Then a matrix with genes in this pathway and related infomations will be returned. This matrix can be used for plot the expression profiles on the pathway figure.