From: Charilaos Skiadas <cskiadas_at_gmail.com>

Date: Tue, 04 Mar 2008 21:25:16 -0500

R-help_at_r-project.org mailing list

https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. Received on Wed 05 Mar 2008 - 02:39:24 GMT

Date: Tue, 04 Mar 2008 21:25:16 -0500

Mark,

if I understand what you are asking, then you likely want either the Floyd-Warshall algorithm:

http://en.wikipedia.org/wiki/Floyd-Warshall_algorithm

or Djikstra's algorithm

http://en.wikipedia.org/wiki/Dijkstra%27s_algorithm

The package igraph seems to have some useful methods, (The shortest.paths method is probably what you want, I think).

How large a graph are we talking about here?

Haris Skiadas

Department of Mathematics and Computer Science
Hanover College

On Mar 4, 2008, at 9:03 PM, Mark W Kimpel wrote:

> I am doing some work the Rgraphviz, a Bioconductor package, but

*> since my
**> question is of a more general nature, thought I would send to this
**> list
**> in hopes that a graph theory expert could answer my question.
**>
**> I wish to do some statistics on node-node relationships. In
**> particular,
**> I want to see if two connected nodes share a common property. I
**> believe
**> that the more "connected" the two nodes are the more likely it
**> would be
**> that they share the property. The graph is highly connected, with a
**> large majority of nodes connected in some fashion.
**>
**> My first question is: can anyone make this real easy and tell me if
**> this
**> has been done and how?
**>
**> If not, I need to start with developing a measure of connectedness
**> that
**> includes degrees of separation and number of edges at each degree. The
**> highest level of connectivity, with weighting 1, would be a first
**> order
**> connection (the graph is undirected). Beyond that, of course, it gets
**> more complicated. To begin, I need to identify the best path
**> between two
**> nodes then characterize that path.
**>
**> Rgraphviz seems to have a fair amount of rendering capabilities, but I
**> don't see many functions to statistically analyze the graph.
**>
**> Thanks,
**> 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
**>
*

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