R/variableZagreb.R

In QuACN: QuACN: Quantitative Analysis of Complex Networks

variableZagreb <- function(g, deg=NULL){
 
  if (class(g)[1] != "graphNEL")
    stop("'g' must be a 'graphNEL' object")
  stopifnot(.validateGraph(g))
  
  if (is.null(deg))
    deg <- graph::degree(g)

  sum(.edgeApply(g, function(from, to) {
    (deg[from] + deg[to] - 2) / (deg[from] * deg[to])
  }, dupls=FALSE))
}