Hi, I encountered a strange behaviour of the add_edges method for DiGraphs (using SAGE 4.5.1). Perhaps this is intended behaviour, but as it seems quiet odd to me I would like to hear the opinion of more experienced (di)graph-users. Maybe this is a real bug...
If I define a looped, multi-edge empty digraph with G=DiGraph({},multi_edges=True,loops=True) I can add a couple of edges at once using G.add_edges([[0,1],[0,1],[1,1],[0,0],[1,0],[0,1]]) this gives the correct graph (having 2 vertices and 6 edges). Nevertheless, if I define my digraph with G=DiGraph(multi_edges=True,loops=True) or G=DiGraph([],multi_edges=True,loops=True) the same command to add edges G.add_edges([[0,1],[0,1],[1,1],[0,0],[1,0],[0,1]]) gives a digraph on 2 vertices but with only 4 edges (the double edge is not created). Even stranger: If I put edge labels I can see that whenever I add more edges afterwards an old edge gets deleted and is replaced by a new one, but never does the graph have multi-edges. Looking forward to an explanation of this funny behaviour. Best M. -- To post to this group, send an email to sage-devel@googlegroups.com To unsubscribe from this group, send an email to sage-devel+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-devel URL: http://www.sagemath.org