[igraph] Calculating total number of paths between two specific nodes

[Xu, Yanjie]

Dear developers of igraph,

 

I am currently using igraph in r to analyse directed acyclic graphs. One of my task is calculating number of all possible paths between the “start” and “end” nodes. With igraph, I can get a list of all possible paths (e.g., from node 1 to node 81) with the code below:

 

>>all_simple_paths(net, 1, 81)

 

Then I summarize how many paths (n) we have:

 

>>n<-length(all_simple_paths(net, 1, 81))

 

This works we my network has around 15 nodes, but we the number of nodes increase, it takes days to calculate “n” for a single network. I have hundreds of networks waiting for calculation. Do you have an idea whether there is a quicker way to get the number of possible paths between two specific nodes? Many many thanks!

 

Best regards,

Yanjie