[Boost-users] Can't link subgraphs because remove_vertex is a TODO

Subject: [Boost-users] Can't link subgraphs because remove_vertex is a TODO
From: Trevor Harmon (Trevor.W.Harmon_at_[hidden])
Date: 2010-10-13 20:15:06

Hi,

I have two directed subgraphs that I want to link together in a  
particular way. To illustrate:

BEFORE
1 ---> 2 ---> 3
4 ---> 5 ---> 6

AFTER
1 ---> 2 ---> 3
   \---> 5 ---> 6

Note that vertex 4 is removed, and the edge that was linking 4 to 5  
now links 1 to 5.

Seems simple enough, but there are two problems, one minor and one  
major:

1) To rewire the edge's source from 4 to 1, I'd like to simply change  
the edge's source. But that doesn't seem possible in Boost. It appears  
I must remove the edge and add a new one with the desired source. This  
can get complicated when it comes to preserving the edge's properties,  
index maps, and such, but hey, at least it's doable.

2) This one I can't work around. Calling remove_vertex on a subgraph  
gives an assertion failure:

Assertion failed: (false), function remove_vertex, file /usr/local/ 
boost_1_43_0/boost/graph/subgraph.hpp, line 733.

It turns out that subgraph's remove_vertex method is not implemented  
at all, which is quite the showstopper for my project. I don't know  
enough about Boost to implement it myself. Any suggestions? Thanks,

Trevor