[igraph] peeling off graphs - minimum spanning tree traversal

[Martin Tomko]

Hi all,
I need to get numbers of vertices in a specific radius from a given 
node, basically "peeling" the shells of the minimum spanning tree.
I am currently doing this:

num<- neighborhood.size(g, r, node) - neighborhood.size(g, r-1, node)

and I have to do it for all r in 1:diameter(g).

Now, it seems unnecessary to compute the neighborhood size separately in 
this way. I thought that either computing the MST and then running the 
neoghborhood.size on that iteratively would help, or using 
graph.neighborhood. Unfortunately, this one does not return a graph 
object. Are there any suggestions?

Cheers
Martin