Re: [Boost-users] [BGL, Graph] listS and property maps

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 wrote:

...

Hi,

I'm new to the BGL and I'm trying to use the strong_components algorithm, defined this way:

template typename property_traits<ComponentMap>::value_type strong_components(Graph& g, ComponentMap comp, const bgl_named_params& params = all defaults)

with a graph defined like this:

typedef adjacency_list 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 > Graph;

For step (2), see the code in the BGL FAQ, #5 (http://tinyurl.com/9skck)

For step (3), first #include , then:

typedef graph_traits<Graph>::vertices_size_type v_size_t; //the range of ComponentMap vector_property_map< v_size_t, property_map::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