watts_strogatz_SW

watts_strogatz_SW.R

################################################################################
# Illustration of the Small-world property in the Watts-Strogatz model.
#-------------------------------------------------------------------------------
library(igraph)
set.seed(1)

avg.stat <- function(nei, p) {
  result <- replicate(1000, {
    wsg <- watts.strogatz.game(1, 100, nei, p)
    c(average.path.length(wsg),
      transitivity(wsg))
  })
  apply(result, 1, quantile, probs = c(0.5, 0.05, 0.95))
}

nei <- 6
p <- 2 ^ -seq(0, 10, len = 21)
result <- sapply(p, avg.stat, nei = nei)
result <- t(result / rep(avg.stat(nei, 0)[1,], each = 3))
par(mar=c(3.2, 2, 0.2, 0.2), mgp=c(2, 1, 0))
matplot(p, result, type = "l", log = "x", xaxt = "n", ylab = "",
        lty = rep(c(1,2,2),2), col=rep(c(1,2), each=3))
axis(1, at = 2 ^ -(0:10),
     labels =  c(1, parse(text = paste(2, 1:10, sep = "^-",
                                       collapse = ";"))))
legend("bottomleft", c("average path length", "clustering coefficient"),
       lty = 1, col = c(1, 2))
#-------------------------------------------------------------------------------