the obvious directed graph structure from root
to leaf nodes (pathway names) is instantiated
for the orthology, nodeData attribute tag
is loaded with the numerical tag for the term in KEGG,
and nodeData attribute depth is loaded with depth
from root
Based on keggorthology read of KEGG orthology, March 2 2010.
Specifically, we run wget on
ftp://ftp.genome.jp/pub/kegg/brite/ko/ko00001.keg and use parsing
and modeling code given in inst/keggHTML to generate a data frame
respecting the hierarchy, and then keggDF2graph to
construct the graph.