R help - Sep 2004 - How to do this "combination" ?

Thanks David first.

Probably, David misunderstood my points.

source vector = (1,2)
the length of the target vector = 3

My expected "complete" outputs should be:
111, 112, 121, 122, 211, 212, 221, 222.

sample(c(1,2),3,replace=TRUE) just gives me one "randomly sampled" 
combination at a time. However, I need the whole list displayed above at a 
time.

Rui

Try:
> m <- as.matrix(expand.grid(1:2, 1:2, 1:2))
> x <- m[,1] * 100 + m[,2] * 10 + m[,3]
> x
  1   2   3   4   5   6   7   8 
111 211 121 221 112 212 122 222 

Note that if the `source vector' is not 1:k for some integer k, you need to
coerce the output of expand.grid, as that returns a data frame of factors.

Andy
> From: wanr at ucalgary.ca
> 
> Thanks David first.
> 
> Probably, David misunderstood my points.
> 
> source vector = (1,2)
> the length of the target vector = 3
> 
> My expected "complete" outputs should be:
> 111, 112, 121, 122, 211, 212, 221, 222.
> 
> sample(c(1,2),3,replace=TRUE) just gives me one "randomly
sampled"
> combination at a time. However, I need the whole list 
> displayed above at a 
> time.
> 
> Rui
> 
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide! 
> http://www.R-project.org/posting-guide.html
> 
>

combinat<-function(els,len){
if (len==1) (return(as.character(els)))
else return(as.vector(t(outer(combinat(els,len-1),as.character(els),
     function(x,y)paste(x,y,sep="")))))
}

combinat(1:2,3)
does what you want



wanr at ucalgary.ca wrote:
> Thanks David first.
> 
> Probably, David misunderstood my points.
> 
> source vector = (1,2)
> the length of the target vector = 3
> 
> My expected "complete" outputs should be:
> 111, 112, 121, 122, 211, 212, 221, 222.
> 
> sample(c(1,2),3,replace=TRUE) just gives me one "randomly
sampled"
> combination at a time. However, I need the whole list displayed above at a 
> time.
> 
> Rui
> 
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide!
http://www.R-project.org/posting-guide.html
> 

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