Hi all, I would like to build a visitor (for dikstra) with the initialise_vertex acting as 'colour map' modifier. I want to exclude some vertices from the search based on a condition. So I want to set some vertices 'black' in the init part of the algorithm. class dijkstra_2step : public boost::default_dijkstra_visitor { public: dijkstra_2step(std::vector<Weight> dists, double threshold): distances(dists), threshold(threshold) {} // THIS PART IS NOT CORRECT!!!! // void initialize_vertex(boost::graph_traits <unGraph>::vertex_descriptor u, const unGraph& g){ if( distances[u] > threshold ) color[u] = black; // ?????? } ////////// std::vector<Weight> distances; double threshold; }; Any help for the above visitor? How to I access the colour? I couldn't find something online. Thanks