Best practices for writing R functions
But beware that a function makes a copy of the argument as soon as you try to modify something in that argument. So, for example, if you have a big list object as an argument and are going to modify one element in the list, you will save memory by making a local copy of the single element and modifying that. However, as others have said, I would not worry until you find there is a problem.
That's generally good practice in R - always modify the simplest object possible. Hadley
Assistant Professor / Dobelman Family Junior Chair Department of Statistics / Rice University http://had.co.nz/