Question

I have an adjacency list defined as shown below. At this point I need to access vertex_descriptor as an int type. How can I do that tvertex source = ...; int source_as_int = ???source??? I remember bumping into this same question before and solved it but don’t remember how and the BGL documentation is useless using it as reference, they should try to take a look at and learn from Javadocs.

Another possibility is to use a possible member function of the vertex_descriptor type or otherwise some of the global BGL functions for this purpose … one never knows where to look for this and they seem to randomly choose between making global functions or member functions, a total fail of an intuitive design if you ask me.

typedef adjacency_list_traits<setS, setS, bidirectionalS> ttraits;

typedef adjacency_list<setS, setS, bidirectionalS,
        // vertex properties
        property<vertex_color_t, default_color_type>,
        // edge properties
        property<edge_capacity_t, int,
        property<edge_residual_capacity_t, int,
        property<edge_reverse_t, ttraits::edge_descriptor> > >, no_property, vecS> tbgl_adjlist_bidir;

typedef graph_traits<tbgl_adjlist_bidir>::vertex_descriptor     tvertex;
typedef graph_traits<tbgl_adjlist_bidir>::edge_descriptor       tedge;
typedef property_map<tbgl_adjlist_bidir, edge_capacity_t>::type tedge_capacity_map;
typedef property_map<tbgl_adjlist_bidir, edge_reverse_t>::type  treverse_edge_map;
typedef property_map<tbgl_adjlist_bidir, vertex_color_t>::type  tvertex_color_map;
typedef graph_traits<tbgl_adjlist_bidir>::out_edge_iterator     tout_edge_iterator;
typedef graph_traits<tbgl_adjlist_bidir>::in_edge_iterator      tin_edge_iterator;

Answer 1

OK I figured it out. Adding the vertex property vertex_index_t solves the problem. I can then access the int index of the vertex like this:

typedef adjacency_list_traits<setS, vecS, bidirectionalS> ttraits;

typedef adjacency_list<setS, vecS, bidirectionalS,
        // vertex properties
        property<vertex_index_t, int,
        property<vertex_color_t, default_color_type> >,
        // edge properties
        property<edge_capacity_t, int,
        property<edge_residual_capacity_t, int,
        property<edge_reverse_t, ttraits::edge_descriptor> > >, no_property, vecS> tbgl_adjlist_bidir;

typedef graph_traits<tbgl_adjlist_bidir>::vertex_descriptor     tvertex;
typedef graph_traits<tbgl_adjlist_bidir>::edge_descriptor       tedge;
typedef property_map<tbgl_adjlist_bidir, edge_capacity_t>::type tedge_capacity_map;
typedef property_map<tbgl_adjlist_bidir, edge_reverse_t>::type  treverse_edge_map;
typedef property_map<tbgl_adjlist_bidir, vertex_color_t>::type  tvertex_color_map;
typedef property_map<tbgl_adjlist_bidir, vertex_index_t>::type  tvertex_index_map;
typedef graph_traits<tbgl_adjlist_bidir>::vertex_iterator       tvertex_iterator;
typedef graph_traits<tbgl_adjlist_bidir>::edge_iterator         tedge_iterator;
typedef graph_traits<tbgl_adjlist_bidir>::out_edge_iterator     tout_edge_iterator;
typedef graph_traits<tbgl_adjlist_bidir>::in_edge_iterator      tin_edge_iterator;

then I use it like this:

    tbgl_adjlist_bidir bgl_adjlist_bidir;
    // ...
    tvertex_index_map indices = get(vertex_index, bgl_adjlist_bidir);
    // ...
    tvertex source; 
    // ...
    int source_as_int = indices[source];