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

Hi all,

source vector = (1,2)
the length of the target vector = 3
 
My expected "complete" output should be:
111, 112, 121, 122, 211, 212, 221, 222 (they are Not numerical numbers, they 
are equivalent to abc and aab etc.).

Not perfect solutions suggested by others so far: 
 
solution1: 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.

solution2: as.matrix(expand.grid(1:2, 1:2, 1:2)) almost implements what I 
need. 

However, in my case, the length of the target vector is not fixed in 
advance. For example, the output might be 11111, 11112, and etc coming from 
the source vector (1,2).

Thanks in advance.

Rui

> n <- 2
> p <- 5
> m <- do.call("expand.grid", data.frame(matrix(rep(1:n, p), n,
p)))
> do.call("paste", c(m, sep=""))
 [1] "11111" "21111" "12111" "22111"
"11211" "21211" "12211" "22211"
"11121"
"21121"
[11] "12121" "22121" "11221" "21221"
"12221" "22221" "11112" "21112"
"12112"
"22112"
[21] "11212" "21212" "12212" "22212"
"11122" "21122" "12122" "22122"
"11222"
"21222"
[31] "12222" "22222"


Please give _all_ the details up front, instead of waiting for people to
guess them.

Andy
> From: wanr at ucalgary.ca
> 
> Hi all,
> 
> source vector = (1,2)
> the length of the target vector = 3
>  
> My expected "complete" output should be:
> 111, 112, 121, 122, 211, 212, 221, 222 (they are Not 
> numerical numbers, they 
> are equivalent to abc and aab etc.).
> 
> Not perfect solutions suggested by others so far: 
>  
> solution1: 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.
> 
> solution2: as.matrix(expand.grid(1:2, 1:2, 1:2)) almost 
> implements what I 
> need. 
> 
> However, in my case, the length of the target vector is not fixed in 
> advance. For example, the output might be 11111, 11112, and 
> etc coming from 
> the source vector (1,2).
> 
> Thanks in advance.
> 
> Rui
> 
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
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> PLEASE do read the posting guide! 
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> 
>

<wanr <at> ucalgary.ca> writes:

: source vector = (1,2)
: the length of the target vector = 3
:  
: solution2: as.matrix(expand.grid(1:2, 1:2, 1:2)) almost implements what I 
: need. 
: 
: However, in my case, the length of the target vector is not fixed in 
: advance. For example, the output might be 11111, 11112, and etc coming from 
: the source vector (1,2).

If the only problem with that solution is that the length is not a parameter
then you could use this variation of it:

   as.matrix(do.call("expand.grid", rep(list(1:2),3)))