|
From: | Christopher Knight |
Subject: | [igraph] unexpected behaviour graph.count.subisomorphisms.vf2 |
Date: | Wed, 5 Sep 2012 13:34:52 +0000 |
Hi,
I'm trying to use graph.count.subisomorphisms.vf2() and graph.get.subisomorphisms.vf2() in R on graphs with coloured edges. However, this doesn't behave as I expect. This could be a bug, or it's possible I've misunderstood something fundamental about
what these functions are meant to do. Specifically:
#create a directed ring graph with alternating edge colours
library(igraph)
g1
<- graph.ring(10,directed=TRUE)
E(g1)$color
<- rep(1:2, length=ecount(g1))
#create a simple A-->B-->C graph with two edge colours
g2<-graph.edgelist(el=matrix(c(1,2,2,3),nrow=2,byrow=TRUE),directed=TRUE)
E(g2)$color<-c(1,2)
#count isomorphisms ignoring colours
graph.count.subisomorphisms.vf2(g1, g2,
edge.color1=NULL,
edge.color2=NULL)
#10 as expected
#count isomorphisms using colours
graph.count.subisomorphisms.vf2(g1, g2)
#6 - I expected 5 (one for each occurrence of a colour in g1) and what these are when looked at with graph.get.subisomorphisms.vf2(g1, g2) seems
inexplicable to me.
#change colours for subgraph edges to the same value, a sequence which doesn't occur in g1 at all, and count isomorphisms again
E(g2)$color<-c(1,1)
graph.count.subisomorphisms.vf2(g1, g2)
#expect a change to zero, but get 6 again
Any help much appreciated.
thanks,
Chris
sessionInfo()
R version 2.15.1 (2012-06-22)
Platform: x86_64-apple-darwin9.8.0/x86_64 (64-bit)
locale:
[1] en_GB.UTF-8/en_GB.UTF-8/en_GB.UTF-8/C/en_GB.UTF-8/en_GB.UTF-8
attached base packages:
[1] stats graphics grDevices utils datasets methods base
other attached packages:
[1] igraph_0.6-2
------------------------------------------------------------------------ |
[Prev in Thread] | Current Thread | [Next in Thread] |