[BioC] Specifying node positions in graphs with Rgraphviz

[Andreas Yankopolus]

I'm trying to plot graphs using Rgraphviz where I specify the node positions and let neato draw the edges. 

According to the Graphviz Wiki (http://www.graphviz.org/mywiki/FaqDotWithNodeCoords), this can be accomplished by specifying "-s -n" on the command line. How do I specify command line options to the layout engine with agopen() or layoutGraph()?

Specifying node locations using nodeAttrs seems straightforward.

Thanks,

Andreas