Strange slow down when exporting to pajek under R

[pms]

I experience fairly big slow down when 'id' field of vertices is defined and I try to export in pajek format, here is an example.

> g=erdos.renyi.game(200000,0.000001); V(g)$id=0:(vcount(g)-1)
> system.time( write.graph(g,file="rand.net.test",format="pajek") )
   user system elapsed
260.136 35.470 295.812
> g=erdos.renyi.game(200000,0.000001);
> system.time( write.graph(g,file="rand.net.test",format="pajek") )
   user system elapsed
  0.008 0.004 0.014

The exported file is around 1MB. This time does not scale linearly e.g.:

> g=erdos.renyi.game(10000,0.000001); V(g)$id=0:(vcount(g)-1)
> system.time( write.graph(g,file="rand.net.test",format="pajek") )
   user system elapsed
  0.560 0.000 0.566
> g=erdos.renyi.game(100000,0.000001); V(g)$id=0:(vcount(g)-1)
> system.time( write.graph(g,file="rand.net.test",format="pajek") )
   user system elapsed
 62.984 3.872 66.899

Meaning that exporting 1 million nodes can be painful...

[Gábor Csárdi (gabor.csardi)]

The development of igraph has moved to github, so please do not comment on this bug here. You are of course welcome to comment on github, here:
https://github.com/igraph/igraph/issues/427