Thanks Aaron, it seems to work. Could you please confirm that the key to use to access the vector_property_map is of type Graph::vertex_descriptor (and not of the type graph_traits<Graph>::vertices_size_type) ? In other words, to access this property map, the code should look like: for(tie(vi,vend) = vertices(g); vi != vend; ++vi){ v_size_t ind = get(index, *vi); cout << "Vertex " << ind<<" is in component " << get(componentMap,*vi) << endl; } and not with "get(componentMap, ind)". Thanks again! Stephane Aaron Windsor wrote:
On 11/15/05, Stephane Grabli <Stephane.Grabli@imag.fr> wrote:
Hi,
I'm new to the BGL and I'm trying to use the strong_components algorithm, defined this way:
template <class Graph, class ComponentMap, class P, class T, class R> typename property_traits<ComponentMap>::value_type strong_components(Graph& g, ComponentMap comp, const bgl_named_params<P, T, R>& params = all defaults)
with a graph defined like this:
typedef adjacency_list<listS,listS,directedS> Graph;
(in particular using listS for vertices storage).
Does anyone know how I should declare the ComponentMap property map? I couldn't figure this out from the documentation and the examples I've seen all assume that a vecS type storage is used for vertices in the graph. Thanks!
Stephane
Here's one way to do it: (1) declare an interior vertex index map. (2) initialize the interior vertex index map. (3) compose the interior vertex index map with a vector property map.
For step (1), just replace your graph declaration with
typedef adjacency_list<listS, listS, directedS, property<vertex_index_t, std::size_t> > Graph;
For step (2), see the code in the BGL FAQ, #5 (http://tinyurl.com/9skck)
For step (3), first #include <boost/vector_property_map.hpp>, then:
typedef graph_traits<Graph>::vertices_size_type v_size_t; //the range of ComponentMap vector_property_map< v_size_t, property_map<Graph, vertex_index_t>::type > component_map( num_vertices(g), get(vertex_index,g) ); //g is an instance of Graph
Now your component_map is ready to use. I haven't tested this code, of course.
Aaron