[BioC] rgraphviz: node attributes of a layout graph

[Laurin Müller]

Hi,

i need to get the parameters (at least coordinates) of a graph after
layouting it with Rgraphviz.

i am trying to add a rectangle to every node in a graph. for a "simple"
graph it works fine (i.e. for the first node):

g <- randomGraph(letters[1:10], 1:4, 0.2)
plot(g, main = "Example Graph")
gl <- agopen(g,name="name")
gv <- AgNode(gl)
x<-getNodeXY(gv[[1]])$x
y<-getNodeXY(gv[[1]])$y
rect(x+30,y,x+40,y+30)

but after layouting the graph i get the old coordinates (before
layouting) for the graph nodes:

names(nLabels) <- nLabels <- nodes(g)
nBorderCols <- rainbow(length(nLabels))
names(nBorderCols) <- names(nLabels)
attrs = list(node=list(fixedsize=FALSE),graph=list(rankdir="LR"))
nodeRenderInfo(g) <- list(label=nLabels, col=nBorderCols)
g <- layoutGraph(g, attrs=attrs)
g<-renderGraph(g)

x<-getNodeXY(gv[[1]])$x
y<-getNodeXY(gv[[1]])$y
rect(x+30,y,x+40,y+30)

i had a look at wolfgang hubers imageMap function and tried to
recalculate the usr coordinates but that does not work:

usr <- par("usr")
w <- getY(upRight(boundBox(gl)))
h <- getX(upRight(boundBox(gl)))
x.u2p = function(x) {(x-usr[1])/diff(usr[1:2])*w}
y.u2p = function(y) {(usr[4]-y)/diff(usr[3:4])*h}
x <- x.u2p(x)
y <- y.u2p(y)
rect(x,y,x+10,y+30)

i am missing something here but do not have a clue were.

thanks in advance,
Laurin

------------------------------------------
Dipl.-Ing. Laurin Mueller
University Assistant at the Institute for Bioinformatics and
Translational Research
UMIT - University for Health Sciences, Medical Informatics and
Technology

Eduard Wallnoefer-Zentrum 1, 6060 Hall in Tyrol, Austria
T +43(0)50 8648 3868, F + 43(0)50 8648 673868
E laurin.mueller at umit.at, W http://bioinf.umit.at