Sorry, g.gml should look like this: graph [ directed 1 node [ id 0 name "a" status "up" ] node [ id 1 name "b" status "up" ] node [ id 2 name "a" status "down" ] node [ id 3 name "b" status "up" ] node [ id 4 name "c" status "down" ] ] As output, you should get: 4 6 These are a list of mappings from sub to g. If you want to access a particular one, for example you can use a_mapping = vertex_mapping_name[index]. Then you can say a_mapping[sub.vertex(0)] to access which vertex in g this maps to. -- View this message in context: http://main-discussion-list-for-the-graph-tool-project.982480.n3.nabble.com/... Sent from the Main discussion list for the graph-tool project mailing list archive at Nabble.com.