[Boost-users] removing parallel edges in the Boost Graph Library?

30 Mar 2004

      I am trying to use BGL to model a directed multigraph, but every time I 
try to remove just one of the edges (u,v), it removes all of the edges 
from u to v.

My graph definition is:
     typedef adjacency_list<listS, listS, bidirectionalS, 
VertexProperty, EdgeProperty> graphdata;

where VertexProperty and EdgeProperty are properties I've defined. 
Everything else seems to work: I have can add parallel edges,  find the 
edge I want to remove based on the EdgeProperty, filter the graph for 
topological sorting, check for existing edges, etc.

In the following, e is of type 
graph_traits<graphdata>::edge_descriptor, and g is the graph of type 
graphdata (defined above):

         std::cout << "about to remove edge\n";
         DumpInfo();
         remove_edge(e, g);
         std::cout << "removed edge\n";
         DumpInfo();

Here is some sample output:
about to remove edge
vertex: 0
	out-edges:
	in-edges: (1,0) (1,0)
	adjacent vertices:
vertex: 1
	out-edges: (1,0) (1,0)
	in-edges:
	adjacent vertices: 0 0
removed edge
vertex: 0
	out-edges:
	in-edges:
	adjacent vertices:
vertex: 1
	out-edges:
	in-edges:
	adjacent vertices:

Note that there were two edges present before the call to remove_edge, 
but only one after.

What am I doing wrong?

I'm using version 1.31, if that helps.

Thanks,
Nicholas Burlett
nrb23@cornell.edu