There're a few solutions to calculating metrics for an assembly.
1.
https://github.com/ajmazurie/velvet-stats
2. Biopieces
3.
http://korflab.ucdavis.edu/datasets/...athon_stats.pl
4. abyss-fac
I don't recommend 1-3. The documentation is bad, I didn't have the time to go through the source code. Biopieces required a multi-stage workflow, which I think it's a very stupid idea.
Use abyss-fac, don't waste your time. On a Mac, install it via "brew install abyss"