spkg dependencies + graph layouts

[Pat LeSmithe]

Partly out of curiosity, I've tried to make a graph of Sage's spkg
dependencies:

http://www.sagenb.org/home/pub/673/

Can anyone recommend settings for laying out this graph elegantly in
Sage? I've also experimented a bit with NetworkX, but my ignorance here
is deep.

GraphViz, which happens to be installed on my machine, seems to do well,
but it would be great to be able to style the vertices and edges
natively. For example, I could use one color for packages written
mostly in pure Python and others for Cython, C / C++, Fortran, and
JavaScript. Styled edges might represent different Makefile commands in
a more general graph.

It would be cool if we could update the graph in real-time with
information about an ongoing build...

[Robert Miller]

> Can anyone recommend settings for laying out this graph elegantly in
> Sage? I've also experimented a bit with NetworkX, but my ignorance here
> is deep.

Posets!

See:

http://www.sagenb.org/home/pub/674/