After running an inference method such as: graph_tool.inference.minimize_blockmodel_dl() I get back a graph_tool.inference.BlockState, which provides a PropertyMap on the vertices which i can use to tell which group a vertex is in. However, if i need to find out all the other members of the same group, (suppose i need to find out who/what else is in the same group as a particular vertex, is there a way to list the groups members other than looping though all vertices and querying their group in the Propertymap? As a bonus, i have a bit of a background in scientific application support as a scientist+sysadmin, so here are Fedora 23/24 graph_tool packages for the Fedora users out there, made with love using the opensuse OBS. http://download.opensuse.org/repositories/home:/theusprom1/Fedora_23/ http://download.opensuse.org/repositories/home:/theusprom1/Fedora_24/ For more info look here: https://build.opensuse.org/package/show/home:theusprom1/graph-tool I second your advise to use the prebuilt packages that the project has already provided, the compile time resources needed are non trivial :(https://build.opensuse.org/package/statistics/home:theusprom1/graph-tool?arc...). I have used these packages (im just getting started though), so YMMV. Best. Theos.