Hi Juan, Sorry for the late response. Juan Manuel Tirado wrote:

I solved the problem by installing the python bindings for graphviz. I did not installed it as appears as optional in the documentation.

Yes, you need the python bindings for graphviz. It is optional, since only needed for graph_draw().

I tried to draw a 250,000 nodes graph and my machine run out of memory (it has 3GB). Have you tested what is the maximum graph size to be drawn in graph-tool?

The problem with drawing large graphs is mostly during the layout... The 'neato' algorithm from graphviz has O(N^2) complexity both in memory use as well as processing time. So, it is unlikely you would be able to draw it, even if you had enough memory. The maximum feasible size with this algorithm is ~1000 nodes. If you want to draw anything larger, you need to provide the positions with the 'pos' parameters, and fix them with the 'pin' parameter. Drawing large graphs is difficult, but there are some good algorithms out there. I plan to include them in graph-tool at a later point. Cheers, Tiago