MAC, yosemite, OS 10.10.3                        Qua Jun 17 18:58:38 BRT 2015
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easy_install pip

pip install mechanize
sudo easy_install pytidylib
sudo -H pip  install matplotlib
sudo -H pip  install scipy
sudo pip install numpy
sudo pip install imaging

export CFLAGS=-Qunused-arguments
export CPPFLAGS=-Qunused-arguments

sudo pip install pillow


svn co https://networkx.lanl.gov/svn/pygraphviz/trunk pygraphviz
cd pygraphviz/
sudo python setup.py install 


Install Graphviz from this page http://www.graphviz.org/Download_macos.php
if you have remove /sw/bin/dot.