Way to get vertex ids that belong to a group

After running an inference method such as:
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?

No, you have to loop.

You can also use the find_vertex() convenience function, which does the
looping for you.

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.
For more info look here:
I second your advise to use the prebuilt packages that the project has
already provided,
the compile time resources needed are non trivial
I have used these packages (im just getting started though), so YMMV.

Thank you for this. Do you intend to maintain these packages in the future?
If yes, I will add a link to it in the graph-tool page.

It would also be a good idea to try to propose these packages for inclusion
into the standard OpenSuse repositories.