
Boost Users : 
From: Aaron Windsor (aaron.windsor_at_[hidden])
Date: 20070605 19:21:02
On 6/5/07, David A. Greene <greened_at_[hidden]> 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<my_graph_type>::vertex_iterator vi, vi_end;
graph_traits<my_graph_type>::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
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