[R] Unordered combinations with repetition

[William Dunlap]

> combnWithRepetition <- function(n, k) combn(n+k-1, k) - seq(from=0, len=k)
> combnWithRepetition(2, 2)
     [,1] [,2] [,3]
[1,]    1    1    2
[2,]    1    2    2
> combnWithRepetition(3, 2)
     [,1] [,2] [,3] [,4] [,5] [,6]
[1,]    1    1    1    2    2    3
[2,]    1    2    3    2    3    3



Bill Dunlap
TIBCO Software
wdunlap tibco.com

On Tue, Jun 9, 2015 at 2:11 AM, Thomas Chesney <
Thomas.Chesney at nottingham.ac.uk> wrote:

> Does anyone know of a function that will return all unordered combinations
> of n elements from a list with repetition?
>
> The combs function in caTools will do this without repetition:
>
> combs(1:2, 2)
>
>      [,1] [,2]
> [1,]    1    2
>
> What I'd like is:
>
> 1 1
> 1 2
> 2 2
>
> Thank you,
>
> Thomas Chesney
>
>
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