Hello, Since my graph use setS as a VertexList, I have to either provide a vertex_index property map for my graph to be able to use some functions requiring a vertex_index (e.g. write_graphviz). My graph is defined as: typedef adjacency_list<setS, setS, undirectedS, NodeData, EdgeData> Graph; Where NodeData and EdgeData are structures. Can you please give me a very simple example of how to provide a vertex_index property map for my graph ? I mean, since an adjacency_list that uses listS or setS as the vertex container does not automatically provide this vertex_id property, how can I add it to the code bellow ? I tried to use an associative_property_map to include index for vertices, but it doesn't work (errors): #include <boost/graph/iteration_macros. hpp> #include <boost/graph/adjacency_list.hpp> using namespace std; using namespace boost; struct NodeData { int label; float influance; /* etc ... */ }; struct EdgeData { int age; /* etc ... */ }; typedef map<vecS, size_t> IndexMap; IndexMap mapIndex; associative_property_map<IndexMap> propmapIndex(mapIndex); typedef adjacency_list<setS, setS, undirectedS, NodeData, EdgeData> Graph; typedef Graph::vertex_descriptor NodeID; typedef Graph::edge_descriptor EdgeID; int main() { Graph g; NodeID n0 = add_vertex(g); g[n0].label = -1; NodeID n1 = add_vertex(g); g[n1].label = -1; EdgeID edge; bool ok; tie(edge, ok) = boost::add_edge(n0, n1, g); if (ok) g[edge].age = 10; int i=0; BGL_FORALL_VERTICES(v, g, Graph) { put(propmapIndex, v, i++); } return 0; } Thanks for answer.