Re: [igraph] unexpected behaviour graph.count.subisomorphisms.vf2

[Tamás Nepusz]

Hi,  

Thanks for the bug report, this has recently been fixed in the R interface:

https://bugs.launchpad.net/igraph/+bug/1032819

There was no new version since then so your best bet is probably to install one 
of the recent nightly snapshots of the R interface; for instance, this one:

http://igraph.googlecode.com/files/igraph_nightly_0.6-2925-20120905.tar.gz  

You can install it with "R CMD INSTALL igraph_nightly_0.6-2925-20120905.tar.gz" 
from the command line. I think you will need the XCode Developer Tools (or any 
working C compiler) to compile it.

--  
T.


On Wednesday, 5 September 2012 at 15:34, Christopher Knight wrote:

> 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
>  
>  
> ------------------------------------------------------------------------
> Dr Christopher Knight Michael Smith Building
> Wellcome Trust RCD Fellow Faculty of Life Sciences
> Tel: +44 (0)161 2755378 The University of Manchester
> room B.2012 Oxford Road
> tinyurl.com/knightLab/ (http://tinyurl.com/knightLab/) Manchester M13 9PT
> · . ,,><(((°> UK
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