Re: [igraph] Simple Graph Analysis

[Gábor Csárdi]

Lorenzo,

On Fri, May 15, 2009 at 2:13 PM, Lorenzo Isella
<address@hidden> wrote:
> Dear All,
> I am trying to do rather basic things with Igraph and R, but I am
> experiencing some problems.
> I paste below one code I am using: it generates a random graph via the
> adjacency matrix.
> First, I try to plot it as it is.
> Second, I highlight its diameter.
> Third (and last): I try to plot the graph and to highlight its largest
> component.
> Probably I am misunderstanding something, since the diameter in the
> second figure I generate does not look like the "longest shortest
> path" (http://mathworld.wolfram.com/GraphDiameter.html)

it definitely does to me. Or can you find a longer shortest path?

> and above all
> when I try to plot the largest cluster of connected nodes in the
> graph, I see also some totally isolated nodes.
[...]
> select_vertices <- V(g)[which(cluster_structure$membership==0)]

Should be

select_vertices <- V(g)[cluster_structure$membership==0]

or

select_vertices <- V(g)[which(cluster_structure$membership==0)-1]

This is the 0/1-based indexing catch.

G.

[...]

-- 
Gabor Csardi <address@hidden>     UNIL DGM