Algorithm to calculate power set (all possible subsets) of a set in R

Question

I couldn\'t find an answer to this anywhere, so here\'s my solution.

The question is: how can you calculate a power set in R?

It is possible to do this with

Answer 1

A subset can be seen as a boolean vector, indicating whether an element is in the subset of not. Those boolean vectors can be seen as numbers written in binary. Enumerating all the subsets of 1:n is therefore equivalent to enumerating the numbers from 0 to 2^n-1.

f <- function(set) { 
  n <- length(set)
  masks <- 2^(1:n-1)
  lapply( 1:2^n-1, function(u) set[ bitwAnd(u, masks) != 0 ] )
}
f(LETTERS[1:4])