Re: [Boost-users] Usage of Transitive_closure().

From: Aaron Windsor (aaron.windsor_at_[hidden])
Date: 2007-10-10 08:18:47

On 10/8/07, nruan <nruan_at_[hidden]> wrote:
> Hi, Aaron,
>     I am sorry it just work one time and doesn't work again I have
> initialized the indexMap, the result show that
> 528 --> 0 0 0 0 0 528 0 0
> 0 --> 0 0
> 0 -->
> 0 --> 0 0 0 0 0 528 0 0
> 0 -->
> 0 -->
> 0 --> 0 0 0
> 0 --> 0 0 0 0 0 528 0 0
>
> my graph sturcture:
>
> // vertex property
> struct VertexProp {
>     size_t id;
>     int level;
>     //for tree instance
>     int pre_order;
>     int post_order;
> };
>
> // edge property
> struct EdgeProp {
>     int id;
>     // for tree or non-tree
>     bool tree; // 1: tree; 0: non-tree
>     bool mark; // 1: processed; 0: not yet
> };
>
> // graph
> typedef adjacency_list<listS, listS, bidirectionalS,
> VertexProp, EdgeProp> Graph;
>
> typedef graph_traits<Graph>::vertex_descriptor Vertex;
> typedef graph_traits<Graph>::edge_descriptor Edge;
>
> my operation code:
>     VertexIndexMap index_map = get(&VertexProp::id, g);
>     graph_traits<Graph>::vertices_size_type count = 0;
>     graph_traits<Graph>::vertex_iterator vi1, vi_end1;
>     for (tie(vi1, vi_end1) = vertices(tc); vi1 != vi_end1; vi1++)
>         index_map[*vi1] = count++;
>     vector<Vertex> to_tc_vec(num_vertices(g));
>     iterator_property_map<Vertex*, VertexIndexMap, Vertex, Vertex&>
>         g_to_tc_map(&to_tc_vec[0], index_map);
>     transitive_closure(g, tc, g_to_tc_map, (index_map));
>
>
> Aaron Windsor wrote:
> > On 10/7/07, Ning Ruan <nruan_at_[hidden]> wrote:
> >
> >> my code to use transitive_closure():
> >>         Graph tc;
> >>         VertexIndexMap index_map = get(&VertexProp::id, g);
> >>         vector<Vertex> to_tc_vec(num_vertices(g));
> >>         iterator_property_map<Vertex*, VertexIndexMap, Vertex, Vertex&>
> >>                 g_to_tc_map(&to_tc_vec[0], index_map);
> >>         transitive_closure(graph, tc, g_to_tc_map, (index_map));
> >>
> >> I use print_graph(tc, get(&VertexProp::id, tc) to print the transitive
> >> graph, then it shows:
> >> 0 --> 0 0 0 0 0 0 0 0
> >> 0 --> 0 0
> >> 0 -->
> >> 0 --> 0 0 0 0 0 0 0 0
> >> 0 -->
> >> 0 -->
> >> 0 --> 0 0 0
> >> 0 --> 0 0 0 0 0 0 0 0
> >>
> >> the result miss the id of vertex, what 's the problem. my original graph
> >> g is correcet:
> >>
> >> 0 --> 1 2 3
> >> 1 --> 4 5
> >> 2 -->
> >> 3 --> 6 7
> >> 4 -->
> >> 5 -->
> >> 6 --> 1
> >> 7 --> 0
> >>
> >
> > Hi Ning,
> >
> > Do you ever initialize the VertexProp::id property? For example:
> >
> > VertexIndexMap index_map = get(&VertexProp::id, g);
> > graph_traits<Graph>::vertices_size_type count = 0;
> > graph_traits<Graph>::vertex_iterator vi, vi_end;
> > for(tie(vi, vi_end) = vertices(tc); vi != vi_end; ++vi)
> >     index_map[*vi] = count++;
> >
> > If you aren't initializing it, that's the problem. If you are
> > initializing it, please show a little more of your code - in
> > particular the typedef you're using for Graph.
> >
> > Regards,
> > Aaron

Hi Ning,

You need to initialize g's vertex index map, not tc's vertex index
map, as per the documentation. Sorry if my previous answer was
misleading - I had a "tc" where a "g" should have been.

Regards,
Aaron