Computes the rich club coefficient for a given degree threshold k.
Measures the tendency of high-degree nodes to connect to each other.
A normalized version compares to random graphs.
# Scale-free networks often show rich-club effectif (requireNamespace("igraph", quietly = TRUE)) {
g <- igraph::barabasi.game(50, m = 2)
network_rich_club(g, k = 5)
}