dDAGroot is supposed to find the root node of a direct acyclic
graph (DAG; an ontology). It return the name (i.e Term ID) of the root
root: the root name (i.e. Term ID)
# 1) load HPPA as igraph object ig.HPPA <-dRDataLoader(RData='ig.HPPA')'ig.HPPA' (from package 'dnet' version 1.0.11) has been loaded into the working environment (at 2017-03-27 19:54:17)g <- ig.HPPA # 2) find the root root <- dDAGroot(g) root "HP:0000118"