Re: [igraph] Confusing results with get_shortest_paths

[Frederik Elwert]

Hello Tamás,

thanks a lot for your quick reply. It turned out it really was stupidity
on my side: I modified the graph during iteration, which of course
yielded unexpected results. Now it works as expected. Sorry for the
noise.

Regards
Frederik



Am Mittwoch, den 17.07.2013, 00:31 +0200 schrieb Tamás Nepusz:
> Hello,
> 
> Your code seems to be fine but I cannot reproduce the issue on my machine -- 
> neither with Python 2.7 nor with Python 3.3.1. Can you send me a 
> self-contained example that constructs the graph from scratch and reproduces 
> the problem on your machine? Also, it would be helpful to know as many 
> details about your platform as possible (i.e. operating system, whether this 
> is a 32-bit or 64-bit machine, whether you have compiled igraph yourself or 
> used an official pre-compiled package, and anything else that you may deem 
> relevant).
> 
> The output from my igraph session is as follows:
> 
> >>> import igraph
> >>> g=igraph.Graph([(0,1),(1,2),(2,3)], directed=False)
> >>> from itertools import combinations
> >>> for s,t in combinations(g.vs, 2):
> ...     g.get_shortest_paths(s,t)[0]
> ... 
> [0, 1]
> [0, 1, 2]
> [0, 1, 2, 3]
> [1, 2]
> [1, 2, 3]
> [2, 3]
> 
> All the best,
> Tamas
> 
> On 16 Jul 2013, at 21:44, Frederik Elwert <address@hidden> wrote:
> 
> > Hello,
> > 
> > I am new to igraph, so I might be getting something wrong. I am using
> > igraph 0.6.5 with python3.
> > 
> > I have a graph and want to calculate the shortest paths between all
> > pairs of nodes:
> > 
> >>>> graph.is_directed()
> >        False
> >>>> graph.get_edgelist()
> >        [(0, 1), (1, 2), (2, 3)]
> >>>> for source, target in combinations(graph.vs, 2):
> >        ...     graph.get_shortest_paths(source, target)[0]
> >        [0, 1]
> >        [0, 1, 2]
> >        [0, 2, 3]
> >        [1, 2]
> >        [1, 0, 3]
> >        [2, 3]
> > 
> > What bothers me: The paths [0, 2, 3] and [1, 0, 3] seem to be invalid.
> > There should be no edge 0 -- 2 or 0 -- 3.
> > 
> > Any hints?
> > 
> > Regards,
> > Frederik
> > 
> > 
> > _______________________________________________
> > igraph-help mailing list
> > address@hidden
> > https://lists.nongnu.org/mailman/listinfo/igraph-help
> 
> 
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