# NOT RUN {
library(igraph)
A <- matrix(c(0, 1, 0, 1, 0, 0, 0, -1, -1, 0,
1, 0, 1, -1, 1, -1, -1, 0, 0, 0,
0, 1, 0, 1, -1, 0, 0, 0, -1, 0,
1, -1, 1, 0, 1, -1, -1, 0, 0, 0,
0, 1, -1, 1, 0, 1, 0, -1, 0, -1,
0, -1, 0, -1, 1, 0, 1, 0, 1, -1,
0, -1, 0, -1, 0, 1, 0, 1, -1, 1,
-1, 0, 0, 0, -1, 0, 1, 0, 1, 0,
-1, 0, -1, 0, 0, 1, -1, 1, 0, 1,
0, 0, 0, 0, -1, -1, 1, 0, 1, 0), 10, 10)
g <- igraph::graph_from_adjacency_matrix(A,"undirected",weighted = "sign")
pn_index(g)
# }
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