[igraph] How to use simplify function for multiple weighted edges?

[epzgwu]

Dear all,

I want to use the fastgreedy function to detect community structures of a weighted graph. Since this method can only treat with simple graphs, I have to invoke the simplify function in R environment such as
>nfgraph = simplify(nfgraph1, remove.multiple = TRUE, remove.loops = TRUE)
This will always be successful for unweighted multiple edges since the only task is to delete all the parallel edges with only one edge left. However, it is a pity that those parallel edges are all with weights, so the weight of the remain edge must be set by the sum of all related weights before the edge deletion is triggered.
My question is, is there any easy way to solve my problem?

Thanks a lot!

Regards

Zhigang Wu