R help - Nov 2009 - searching code for combination of vector

For a given numeric vector v of length n and sum s, is there a ready- 
to-run code that returns every combination of v in n summing up to s?  
Example for n=3 and s=2:

v <- c(2, 0, 0)
# find some coding here that returns
[1] 2 0 0
[2] 1 1 0
[3] 1 0 1
[4] 0 2 0
[5] 0 1 1
[6] 0 0 2

Thanks

S?ren

-- 
S?ren Vogel, Dipl.-Psych. (Univ.), PhD-Student, Eawag, Dept. SIAM
http://www.eawag.ch, http://sozmod.eawag.ch

soeren.vogel at eawag.ch wrote:
> For a given numeric vector v of length n and sum s, is there a 
> ready-to-run code that returns every combination of v in n summing up to 
> s? Example for n=3 and s=2:
> 
> v <- c(2, 0, 0)
> # find some coding here that returns
> [1] 2 0 0
> [2] 1 1 0
> [3] 1 0 1
> [4] 0 2 0
> [5] 0 1 1
> [6] 0 0 2
Function comb() in pkg:forensim does just that.

  -Peter Ehlers
> 
> Thanks
> 
> S?ren
>