[R] enumerate subsets

[Peter Dalgaard]

lamack lamack wrote:
> Dear all, is there a R function that enumerate a partition of a vector of size n? (of course for n not very large).
> I would like enumerate all the (2 power n)-1 sub-sets. (2 power n)-1 since (2 power n) includes de empty subset.
>
> Best Regards.
>
> ps. It is not a homework. I never posted homework in this list.
>
>   
The easiest way is probably to generate the numbers 1:(2^n-1), convert 
them to binary, and use the bits to indicate in/out status.

E.g.,

n <- 4
x <- 1:(2^n-1)
sapply(1:n, function(i) {r <- as.logical(x%%2)  ; x <<- x%/%2 ; r})
 

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