Graph permutation with some constraints.

graph_permut.r

library(igraph)
library(plyr)

nl <- function(gl) sum(aaply(gl, 1, function(x) x[1] == x[2]))
nd <- function(gl) nrow(gl) - nrow(unique(aaply(gl, 1, sort)))

permut_graph <- function(g){
   gl <- get.edgelist(g)
   L <- nl(gl)
   D <- nd(gl)
   N <- nrow(gl)
   diff_L <- TRUE
   diff_D <- TRUE
   diff_N <- TRUE
   while(diff_L | diff_D | diff_N)
   {
      tgl <- gl
      tgl[,2] <- sample(tgl[,2])
      tgl <- unique(tgl)
      diff_L <- nl(tgl) != L
      diff_D <- nd(tgl) != D
      diff_N <- nrow(tgl) != N
   }
   return(graph.edgelist(tgl))
}

par(mfcol=c(2,2))
g <- graph.de.bruijn(2, 3)
plot(g)
for(i in 1:3) plot(permut_graph(g))