Using the igraph
package:
x <- matrix(c(0,2,1,1,2,0,1,0,1,1,0,1,1,0,1,0), 4, 4)
rownames(x) <- colnames(x) <- LETTERS[1:4]
library(igraph)
g <- graph.adjacency(x)
get.edgelist(g)
# [,1] [,2]
# [1,] "A" "B"
# [2,] "A" "B"
# [3,] "A" "C"
# [4,] "A" "D"
# [5,] "B" "A"
# [6,] "B" "A"
# [7,] "B" "C"
# [8,] "C" "A"
# [9,] "C" "B"
# [10,] "C" "D"
# [11,] "D" "A"
# [12,] "D" "C"
I would also recommend you spend some time reading the igraph
documentation at http://igraph.sourceforge.net/index.html since a lot of your recent questions are all simple case usages.
(As a bonus, plot(g)
will answer your other question How to plot relationships in R?)