Thanks for the explanation and workarounds！
On Wed, Dec 11, 2013 at 9:26 PM, Tamás Nepusz <[email protected]> wrote: > Hi, > > Thanks for the bug report - I have fixed this now in the development > branch: > > > https://github.com/igraph/igraph/commit/043577090ce13b00fa86b1ccf844b1149d251ebd > > FWIW, the problem happens only if igraph decides to use the Bellman-Ford > algorithm to calculate the shortest paths. In the Python interface, this > happens if the graph has at least one negative or zero edge weight, the > number of target vertices is not larger than 100 and the “mode” argument of > the shortest_path() call is equal to “out”. As a workaround, you could > either: > > 1) omit the target vertex from the call or specify more than 100 target > vertices > 2) use mode=“all” or mode=“in” instead of mode=“out”. If you really need > mode=“out”, you can swap the direction of each edge, swap the target node > with the source node in the call and use mode=“in” instead. > 3) eliminate negative or zero weights from your graph > > All the best, > -- > T. > > > On Wednesday, 11 December 2013 at 11:15, Yaohua Xiong wrote: > > > Hi, > > > > I'm relative new to the igraph lib and encounters a weird problem. The > problem is boiled down like this: > > > > given following code snippet > > """ > > # initialize a graph with postive attribute "imp_tt" > > for i in range(1000): > > sp = graph.shortest_paths(sidx, tidx, weights="imp_tt")[0][0] > > > > """ > > for a small graph of 1000+ vertices, this code snippet works perfectly. > > But for a bigger graph of 10000+ vertices the code crash with > > """ > > python: igraph_error.c:173: IGRAPH_FINALLY_REAL: Assertion `no<100' > failed. > > Aborted > > > > """ > > after about 100 iterations. > > > > However if I delete the weights="imp_tt" part it works again. > > > > I searched the archive and get a sense that it involves a stack not get > released. But then why it doesn't need to be explicitly released for the > small graph? > > > > Any Ideas what's going wrong? > > > > Best Regards, > > Yaohua Xiong > > > > -- > > M.Sc. Engg Yaohua Xiong > > > > Universität Stuttgart > > Lehrstuhl für Verkehrsplanung und Verkehrsleittechnik > > _______________________________________________ > > igraph-help mailing list > > [email protected] (mailto:[email protected]) > > https://lists.nongnu.org/mailman/listinfo/igraph-help > > > > > _______________________________________________ > igraph-help mailing list > [email protected] > https://lists.nongnu.org/mailman/listinfo/igraph-help > -- M.Sc. Engg Yaohua Xiong Universität Stuttgart Lehrstuhl für Verkehrsplanung und Verkehrsleittechnik
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