R help - Aug 2006 - Rgraphviz - neato layout - edge weights do not have an effect

Dear all,

neato makes layouts according to a physical model in which the length of 
the edges is determined by springs. The weight of the edge is the 
strength of the spring. However, I was not able to find any influence of 
edge weight on the layout. In the 
http://www.graphviz.org/Documentation/neatoguide.pdf the attribute
"len"
is another parameter of the neato layout.

set.seed(31)
V=letters[1:5]
g2=randomEGraph(V,0.5)
plot(g2,"neato",main="All weights 1")

# change and edge weight
edgeData(g2, from = "d", to = "e", attr =
"weight") <- 20
plot(g2,"neato",main="Nothing changed!")

#try out length attribute change
edgeDataDefaults(g2,"len")=1
edgeData(g2, from = "d", to = "e", attr = "len")
<- 5
plot(g2,"neato",main="Nothing changed again!")


Has anyone an idea how to achieve a change in the graph layout ?

Best

Franz Quehenberger

-- 
--
Franz Quehenberger
Institute for Medical Informatics, Statistics and Documentation
Graz, Austria

Hi Franz,

This might be better directed to the bioconductor mail list.

Franz Quehenberger <franz.quehenberger at meduni-graz.at>
writes:
> Dear all,
>
> neato makes layouts according to a physical model in which the length
> of the edges is determined by springs. The weight of the edge is the
> strength of the spring. However, I was not able to find any influence
> of edge weight on the layout. In the
> http://www.graphviz.org/Documentation/neatoguide.pdf the attribute
> "len" is another parameter of the neato layout.
>
> set.seed(31) V=letters[1:5] g2=randomEGraph(V,0.5)
> plot(g2,"neato",main="All weights 1")
>
> # change and edge weight edgeData(g2, from = "d", to =
"e", attr > "weight") <- 20
plot(g2,"neato",main="Nothing changed!")
>
> #try out length attribute change edgeDataDefaults(g2,"len")=1
> edgeData(g2, from = "d", to = "e", attr =
"len") <- 5
> plot(g2,"neato",main="Nothing changed again!")
>
>
> Has anyone an idea how to achieve a change in the graph layout ?
Have you read through the Rgraphviz vignettes?  

Rgraphviz currently ignores attributes of the graph.  This is
currently by design: display attributes are Rgraphviz's business.
There are ways to specify node and edge attributes for Rgraphviz, but
I'm not sure if the feature you want is implemented.

+ seth