[igraph] add vertex label shortest path

[joe j]

This would be a straight forward thing to do, but I can't figure out how.

Basically I want the output of 'shortest.paths' in three columns:
"vertex1", "vertex2", "shortestpath", as the code below shows.

However instead of the numeric id's which igraph has assigned to the
vertices (vertex1 & vertex2 in the example below) I would like to have
the vertex names that are there in the graph object y.


#code for generating shortest path matrix and creating a 3 columns
y_s<-shortest.paths(y,  weights = NULL)
y_s <- melt(y_s)[melt(upper.tri(y_s))$value,]
names(y_s) <- c("vertex1", "vertex2", "shortestpath")

Cheers,
Joe.