I have been using RcppArmadillo more and more frequently, so thought I would make a cheatsheet/cookbook type reference that translates common R operations into equivalent arma code.
I have put them up on a github wiki page here.
The functions are all pretty basic and not particularly robust. In particular they do not do any bounds or sanity checking.
You might also enjoy the arma documentation, in particular the matlab/octave syntax conversion example.
There is also an excellent book Seamless R and C++ Integration with Rcpp
Any corrections or additions are most welcome.