[R] vertex labels in igraph from adjacency matrix

[Mark W Kimpel]

Looks like I turned an "off my one error" into an "off by two error" by 
adding rather than subtracting. Clearly a logic error on my part.

Also, which.max is clearly superior as it results in half as many 
function calls.

Thanks guys!

As an aside, although igraph may use the C indexing convention, R users 
and their code, is much more in tune with indexing beginning at 1. 
Adjusting this in the R interface to igraph may solve many headaches 
down the road.

Mark

Mark W. Kimpel MD  ** Neuroinformatics ** Dept. of Psychiatry
Indiana University School of Medicine

15032 Hunter Court, Westfield, IN  46074

(317) 490-5129 Work, & Mobile & VoiceMail
(317) 204-4202 Home (no voice mail please)

mwkimpel<at>gmail<dot>com

******************************************************************


Gabor Csardi wrote:
> On Wed, Mar 05, 2008 at 02:27:21AM -0500, Charilaos Skiadas wrote:
> [...]
>> Btw, you will likely want to take the betweenness call out, and call  
>> it once and store the result, instead of calling it twice (well,  
>> assuming the graph is largish). Or even better, use which.max:
>>
>> which.max(betweenness(graph = my.graph, v=V(my.graph), directed =  
>> FALSE))
> 
> This is almost good, but there is a catch, in igraph vertices are 
> numbered from zero. So if you want an igraph vertex id, then you 
> need to subtract one from this, i.e.:
> 
> maxb <- which.max(betweennness(my.graph, directed=FALSE))-1
> 
> You can double check it:
> 
> betweenness(my.graph, maxb, directed=FALSE)
> 
> Gabor
> 
> PS. there is also an igraph mailing list, see the igraph homepage
> at igraph.sf.net
> 
>> Haris Skiadas
>> Department of Mathematics and Computer Science
>> Hanover College
>>
> [...]
>