Re: [Boost-users] [BGL] topological_sort compile error

On 6/5/07, David A. Greene wrote:

On Monday 04 June 2007 21:06, Aaron Windsor wrote:

...

The error you're seeing (both in your code and the example you included) is caused because the topological sort algorithm expects a vertex index map - if you don't provide one as a parameter, it uses whatever interior vertex index map the graph has. Even if you declare a vertex index map as an interior property of the graph, you still have to initialize it by mapping each vertex to an integer in the range 0..num_vertices(g)-1. See #5 in the BGL FAQ (http://www.boost.org/libs/graph/doc/faq.html) for an example of how to initialize one.

Ok, that makes sense.

How do I add a vertex index map property to a graph that already has bundled properties? The FAQ example assumes property lists.

Or do I need to use an external property?

Thanks again for your help.

-Dave

Hi Dave, In your example, you could just add an "index" field to the vertex_bundle structure that you're already using. Then, after initializing the index with something like: graph_traits::vertex_iterator vi, vi_end; graph_traits::vertices_size_type current_index = 0; for(tie(vi,vi_end) = vertices(g); vi != vi_end; ++vi) g[*vi].index = ++current_index; //g is the current graph You should be able to call the topological sort algorithm as follows (within the context you described earlier, having an iterator t over such graphs): topological_sort(*t, std::back_inserter(rev_topo_order)), vertex_index(get(&vertex_bundle::index, *t))); Regards, Aaron