This short post is to share an R tip Pierre recently gave me. When you need to store values sequentially (typically inside a loop), it’s more far efficient to create the whole vector (or matrix) and to fill it, rather than to concatenate the values to your current vector (or matrix). In terms of allocation 
Zero Inflated Models and Generalized Linear Mixed Models with R.
Zuur, Saveliev, Ieno (2012).
