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