rev provides a reversed version of its argument. It is generic
function with a default method for vectors and one for
dendrograms. Note that this is no longer needed (nor efficient) for obtaining
vectors sorted into descending order, since that is now rather more
directly achievable by
sort(x, decreasing = TRUE).
- a vector or another object for which reversal is defined.
Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.
x <- c(1:5, 5:3) ## sort into descending order; first more efficiently: stopifnot(sort(x, decreasing = TRUE) == rev(sort(x))) stopifnot(rev(1:7) == 7:1) #- don't need 'rev' here
# My Favourite Animals animals_ls = list(animals = c("Dog", "Elephant", "T-Rex"), intuitive_size = c("Small", "Medium", "Huge"), speed_in_km = c(55,40,40)) animals_ls # My Favourite Animals in reversed order reversed_animals_ls = rev(animals_ls) # Is it the same? identical(animals_ls, reversed_animals_ls) identical(animals_ls, animals_ls)