How to calculate single source shortest paths

[Bonsanto]

Hello, there is a library for Python called networkx, and it has an interesting functionality I couldn't find in jgrapht, which is the possibility of calculating all reachable vertexes from given vertex and with a distance smaller than a threshold (see example here).

e.g.

>>> G=nx.path_graph(5)
>>> length=nx.single_source_shortest_path_length(G,0)
>>> length[4]
4
>>> print(length)
{0: 0, 1: 1, 2: 2, 3: 3, 4: 4}