Grandalf is a python package made for experimentations with graphs drawing
algorithms. It is written in pure python, and currently implements two layouts:
the Sugiyama hierarchical layout and the force-driven or energy minimization
approach. While not as fast or featured as graphviz or other libraries like OGDF
(C++), it provides a way to walk and draw graphs no larger than thousands of
nodes, while keeping the source code simple enough to make it possible to easily
tweak and hack any part of it for experimental purpose.