Re: [Boost-users] [BGL]Standard Breadth First Visitor

On Tue, 2009-01-06 at 09:03 -0500, Andrew Sutton wrote:

I can't seem to wrap my head around implementing a BFS Visitor and color map required by the breadth_first_visitor function.

I want to use it to find connected parts of a graph and after the algorithm has run I plan to clear all white nodes.

If anyone could provide me with a code example or link to one implementing really only default behaviour I'd appreciate it immensely.

Which part is causing trouble: the implementation of the visitor or the creation of a color map? Creating exterior properties can be a bit tricky, and the method used depends entirely on the type of your graph.

Post code usually results in better answers.

Andrew Sutton andrew.n.sutton@gmail.com _______________________________________________ Boost-users mailing list Boost-users@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

OK, I'll try to explain a little bit better. I have a graph with a known number of roots which I represent by the following adjacency list: boost::adjacency_list The graph is generated in a way that I have a stable number of vertices but sort of random links (it's an evolutionary design of a network). So I want to use the breadth first visitor to identify any vertices of the graph that are not connected to the main graph formed with the known roots. Since I have several roots I thought I could speed up the process by using an external property map for colours which I pass again to breadth_first_visitor without re-initialisation for each root. At the end I would clear any vertex that is white. When I want to use the algorithm: template void breadth_first_visit (const IncidenceGraph& g, typename graph_traits<IncidenceGraph>::vertex_descriptor s, Buffer& Q, BFSVisitor vis, ColorMap color) I need to supply it with an appropriate visitor which does the exploring of adjacent nodes and a property map for the colouring. Setting up those two causes me trouble. I simply fail at making sense of the documentation. Thank you for your help and time, Moritz