[R] combinations without repetition

[Adaikalavan Ramasamy]

This can be simplified slightly by 
 unique( t( sapply( permn( c(1,1,0) ), "c" )  ) )


Here is another possibility :

 a <- expand.grid( 0:1, 0:1, 0:1 )
 a[ which( rowSums(a) == 2 ),  ]

which gives

  Var1 Var2 Var3
4    1    1    0
6    1    0    1
7    0    1    1


Regards, Adai



On Sun, 2005-02-13 at 10:33 -0500, John Fox wrote:
> Dear Marcelo,
> 
> This is, I guess, permn() in the combinat package.
> 
> How about unique(matrix(unlist(permn(c(1,1,0))), ncol=3, byrow=TRUE)), which
> leaves the permutations in the rows of a matrix?
> 
> I hope this helps,
>  John
> 
> --------------------------------
> John Fox
> Department of Sociology
> McMaster University
> Hamilton, Ontario
> Canada L8S 4M4
> 905-525-9140x23604
> http://socserv.mcmaster.ca/jfox 
> -------------------------------- 
> 
> > -----Original Message-----
> > From: r-help-bounces at stat.math.ethz.ch 
> > [mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of 
> > mjenny at rumms.uni-mannheim.de
> > Sent: Sunday, February 13, 2005 9:45 AM
> > To: r-help at stat.math.ethz.ch
> > Subject: [R] combinations without repetition
> > 
> > The solution is probably simple but I need someone to point me to it.
> > How can I reduce the following 6 permutations to the 3 unique 
> > combinations
> > (1,1,0) (1,0,1) (0,1,1)?
> > 
> > permn(c(1,1,0))
> > [[1]]
> > [1] 1 1 0
> > 
> > [[2]]
> > [1] 1 0 1
> > 
> > [[3]]
> > [1] 0 1 1
> > 
> > [[4]]
> > [1] 0 1 1
> > 
> > [[5]]
> > [1] 1 0 1
> > 
> > [[6]]
> > [1] 1 1 0
> > 
> > Thanks a lot
> > Marcelo Jenny
> > 
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