The chemical similarity network or CSN is a great tool for organizing biological data based on known biochemistry or chemical structural similarity. Here is an example CSN for visualizing metabolomic changes (measured via GC/TOF) due to anaerobic stress in germinating seeds. In this network edges are formed for chemical similarity scores > 75. Node color describes 






Zero Inflated Models and Generalized Linear Mixed Models with R.
Zuur, Saveliev, Ieno (2012).