If you, like me, are trying to use the improved source code for the Louvain method, you may encounter the same bug I stumbled into. I compiled it on a plain Ubuntu machine and even using the sample graph raises a segmentation fault.
Valgrind showed that the program writes beyond the end of an array.
I don’t know if it is a bug, a problem of moving code from C to C++ or a change in the underlying implementation of std::vector occurred after the original source code was distributed.
However, if you need the patch, write me a line. I’m going to contact the original author to tell him about the problem (and the possible solution, if this is an actual bug and not a problem with g++).