[R] searching code for combination of vector

[soeren.vogel at eawag.ch]

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

Sören

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