Re: [Boost-users] [boost][graph] write_graphviz problem

From: Aaron Windsor (aaron.windsor_at_[hidden])
Date: 2007-08-06 22:35:46

On 8/6/07, David Callu <ledocc_at_[hidden]> wrote:
> Hi,
>
>     I try to write my graph to std::cout with boost::write_graphviz.
>     In the example boost/libs/graph/example/graphviz.cpp,
>     the graph used is a
>           boost::adjacency_list<vecS, vecS, directedS,
>                                           property<vertex_name_t,
> std::string>,
>                                           property<edge_weight_t, double> >
>
>     and all work fine.
>
>
>     my graph is a
>
>           boost::adjacency_list<listS, listS, bidirectedS,
>                                            property<my_vertex_t, my_vertex>,
>                                            property<my_edge_t, my_edge>,
>                                           property<my_graph_t, my_graph> ,
>                                           listS >
>
>     If a do "write_graphviz(std::cout, g);"
>     I have a very big error.  (why BGL didn't use boost concept check ???)
>     I search in boost code and i found !!!
>     In the file boost/graph/graphviz.hpp line 257    (boost 1.34)
>     "out << get(vertex_id, *i);"

<snip>

>
>    In the complete signature function :
>    void write_graphviz(std::ostream &, const VertexListGraph & g
>                                  vertexPropertyWrite vpw,
>                                  EdgePropertyWriter epw,
>                                  GraphPropertyWriter gpw,
>                                  VertexID vertex_id);
>
>
>     I can give the property_tag to used in the function.
>     But, In opposition to other BGL algorithm which accept an external
> PropertyMap,
>     this property must be in the graph. And I don't want to add a index
> property.
>
>
>    Question :
>       How to use write_graphviz algorithm with boost::adjacency_list<listS,
> listS> ?
>
>       Is there a magic boost property tag to use with a
> boost::adjacency_list<listS, listS>
>       like the boost::vertex_index_t tag and the boost::adjacency_list<vecS,
> vecS>
>
>       is there another solution ??

Hi David,

write_graphviz takes a parameter "vertex_id", of type "VertexID",
where VertexID is any type that models the readable property map
concept. If you don't provide one, the algorithm looks for one by
calling get(vertex_index, g) - which gets the interior vertex index.
The vertex_id parameter is an actual property map - it's supposed to
map each vertex in the graph to a distinct non-negative integer in the
range [0,1,...,num_vertices(g)). If, as you say, you don't want to add
an interior property to do this, you need to (1) create an exterior
property map and pass it as the vertex_id parameter (see
http://tinyurl.com/yhju58 for more information on how to do this) and
(2) explicitly pass this vertex index map to the function, instead of
allowing it to default to the interior index.

Regards,
Aaron