Looks great!
One thing R really needs is some sort of dead simple pass-by-reference mechanism for functions. Creating copies object copies every time you call a function on an object is a real performance killer.
One thing R really needs is some sort of dead simple pass-by-reference mechanism for functions. Creating copies object copies every time you call a function on an object is a real performance killer.
Of course that doesn't help in the case where you do want the called function to modify the data, but in-place rather than by making a copy.