Hi

given a graph G I want to compute a corresponding reachability graph; that

is, for a given distance r, if the distance between two vertices is less

than r they are joined by an edge.

The shortest_distance function with the Johnson algorithm works fine but

returns the distances between all pairs of vertices's and not just those

with a distance less than r. Iterating through all distances and finding

those with distance less than r is one solution but this is incredibly slow

due to the size of my graph.

Have you any suggestions? I’m considering using the breath first search

functionality but I don’t think there is an option to terminate the search

on parts the search tree with distance greater than r.

thanks in advance