[R] Minimum Spanning Tree

[jpearl01]

Make the graph undirected first and then choose the right plotting
parameters. E.g. the following works fine for me:

set.seed(2)
g <- erdos.renyi.game(100, 300, type="gnm", directed=TRUE)
E(g)$weight <- runif(ecount(g))
mst <- minimum.spanning.tree(g)

mst <- simplify(as.undirected(mst))
lay <- layout.reingold.tilford(mst, root=which.max(degree(mst))-1)
plot(mst, layout=lay, vertex.size=5, asp=FALSE, vertex.color=NA,
       vertex.frame.color=NA)

G.


Thanks for all your help Gabor,  However, I'm unable to get a display in R
which is at all readable.  I'm not sure why that is (if the data is
generated randomly, like in your example the tree builds/reads fine...
however on my dataset whichever node is picked as the root just completely
over powers the rest of the nodes which all clump together in a manner that
is unreadable).  My dataset is:
http://www.nabble.com/file/p22957493/sp_matrix.csv sp_matrix.csv 
If you would like to take a look.  However, as it stands I think I'll have
to find another option.  Thanks again for all your efforts.

~josh
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