Re: [Boost-users] [BGL] Is vertex_descriptor always integer?

Subject: Re: [Boost-users] [BGL] Is vertex_descriptor always integer?
From: Ireneusz Szcześniak (irek.szczesniak_at_[hidden])
Date: 2015-12-05 18:26:23

Daniel, thank you for you answer.

As you suggested, I tied to use make_iterator_property_map:

     std::vector<edge_descriptor> pred_vec(num_vertices(g));
     auto pred = make_iterator_property_map(pred_vec.begin(), 
get(vertex_index_t(), g));
     auto rep = record_edge_predecessors(pred, on_edge_relaxed());

My code compiled for:

boost::adjacency_list<boost::vecS, boost::vecS, boost::bidirectionalS>

but not for:

boost::adjacency_list<boost::vecS, boost::listS, boost::bidirectionalS>

Am I doing something wrong?

As for another solution, my guess is that for a mapping from any kind 
of vertex_descriptor to edge_descriptor, one could use 
associative_property_map.  Would that be true?

Thanks & best,
Irek

On 04.12.2015 17:30, Daniel Hofmann wrote:
> For the concept a vertex_descriptor models, take a look here:
>
>> http://www.boost.org/doc/libs/1_59_0/libs/graph/doc/Graph.html
>
>> A vertex descriptor corresponds to a unique vertex in an abstract graph instance. A vertex descriptor must be Default Constructible, Assignable, and Equality Comparable.
>
> These are the guarantees you get.
>
> I'm usually using make_iterator_property_map with a vector of the graph's vertex or edge descriptor.
>
> Hope that helps,
> Daniel J H
>
> On December 4, 2015 4:07:58 PM GMT+01:00, "Ireneusz Szcześniak" <irek.szczesniak_at_[hidden]> wrote:
>> Hi,
>>
>> In my code I do:
>>
>> vector_property_map<edge_descriptor> pred(num_vertices(g));
>> auto rep = record_edge_predecessors(pred, on_edge_relaxed());
>> auto dv = make_dijkstra_visitor(rep);
>> dijkstra_shortest_paths(g, s, visitor(dv));
>>
>> But this assumes that the vertex_descriptor is integer, since I'm
>> using vector_property.
>>
>> Does this assumption always hold, or should I choose the type of the
>> property map based on the graph type?
>>
>>
>> Thanks & best,
>> Irek
>> _______________________________________________
>> Boost-users mailing list
>> Boost-users_at_[hidden]
>> http://lists.boost.org/mailman/listinfo.cgi/boost-users
>
> _______________________________________________
> Boost-users mailing list
> Boost-users_at_[hidden]
> http://lists.boost.org/mailman/listinfo.cgi/boost-users
>