Illustration for calculating betweeness by the method suggested

library(igraph) g <- c(‘a’, ‘b’, ‘a’, ‘c’, ‘a’, ‘d’, ‘a’, ‘e’, ‘c’, ‘d’, ‘d’, ‘e’, ‘e’, ‘f’, ‘e’, ‘g’, ‘f’, ‘g’) org.graph <- graph(edges = g, directed = F) V(org.graph)$names <- letters[1:7] J <- neighbors(org.graph, v = ‘a’) par(mfrow = c(1,2)) plot.igraph((org.graph), main = ‘Original Graph’) mod.graph <- delete.vertices(org.graph, ‘a’) plot.igraph((mod.graph), main = ‘Graph with node “a” removed’)

The inbuilt function closeness.estimate would be used for calculating node specific

closeness values. However, note that these estimates are not normalised.

C1 <- closeness.estimate(org.graph,vids = J\(names,cutoff=7) C1 C2 <- closeness.estimate(mod.graph,vids = J\)names,cutoff=7) C2 betw.a <- (sum(C1) - sum(C2))/sum(C1)

betw.a