Hi, I have modified the astar-cities.cpp example to use an external rank_map based on iterator_property_map. The following should give you an idea: vector<cost> v_vec(num_vertices(g), 0.0); typedef property_map< mygraph_t, vertex_index_t>::type VertexIndexMap; VertexIndexMap v_index = get(vertex_index, g); // Initialization of interest // Create the external property map typedef iterator_property_map< std::vector< cost >::iterator, VertexIndexMap
CostMap; CostMap c_map(v_vec.begin(), v_index);
and the function-call of astar_search is as follows: astar_search (g, start, distance_heuristic<mygraph_t, cost, location*, const char**> (locations, goal, name), predecessor_map(&p[0]).distance_map(&d[0]). visitor(a_star_vis). rank_map(c_map)); // Here we use the "global" cost map Basically, the code is the same as in the example, with only the addition of the explicit rank_map. Now I am fairly confused that the function call seems to behave the same if I have "get(vertex_index, g)" and if I don't have it. This comes unexpected to me as I would think that it needs OffsetMap (v_index) to correctly find the index in the random access container (v_vec). But when I simply declare an object it is not yet initialized and will not contain any meaningfull offsets (not using "get(vertex_index, g)"). So why does it work, when the map is not initialized? Or what am I missing here please? Best, Cedric