[R] all possible subsets of r out of n

[Warnes, Gregory R]

The gregmisc package contains the function 'combinations'.

One you install gregmisc, the code

	library(gregmisc)
	combinations(10, 3, letters[1:10])

should give you what you want.

-Greg 

> -----Original Message-----
> From: Yuelin Li [mailto:yuelin at mail.med.upenn.edu]
> Sent: Wednesday, August 28, 2002 12:28 PM
> To: r-help at stat.math.ethz.ch
> Subject: [R] all possible subsets of r out of n
> 
> 
> Has anyone written a function that returns all possible
> subsets of r elements out of a vector that contains n
> elements?  I have not been able to find an answer in the FAQ
> or the archives.
> 
> Say I have a vector: letters[1:10].  I want to get a matrix
> of 120 rows that contains all possible subsets of 3 letters
> out of the 10.  And I would like to be able to generalize to
> any r out of n, like function(x=letters[1:10], r=3) that
> returns:
> 
> a, b, c
> a, b, d
> a, b, e
> ...
> 
> etc.
> 
> Many thanks in advance,
> 
> - Yuelin Li.
> 
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