Split a vector into chunks in R

Question

I have to split a vector into n chunks of equal size in R. I couldn't find any base function to do that. Also Google didn't get me anywhere. So here is what I came up with, hopefully it helps someone some where.

x <- 1:10
n <- 3
chunk <- function(x,n) split(x, factor(sort(rank(x)%%n)))
chunk(x,n)
$`0`
[1] 1 2 3

$`1`
[1] 4 5 6 7

$`2`
[1]  8  9 10

Any comments, suggestions or improvements are really welcome and appreciated.

Cheers, Sebastian

Answer 1

If you don't like split() and you don't like matrix() (with its dangling NAs), there's this:

chunk <- function(x, n) (mapply(function(a, b) (x[a:b]), seq.int(from=1, to=length(x), by=n), pmin(seq.int(from=1, to=length(x), by=n)+(n-1), length(x)), SIMPLIFY=FALSE))

Like split(), it returns a list, but it doesn't waste time or space with labels, so it may be more performant.