[R] How to create arbitrary number of loops in R

[ilai]

To cbind, you don't need a loop

(M <- matrix(1:50,nc=10))
c2way <- combn(ncol(M),2)
MM <- M[,c2way]
dim(MM) <- c(nrow(M),nrow(c2way),ncol(c2way))
MM

c3way <- combn(ncol(M),3)
MMM <- M[,c3way]
dim(MMM) <- c(nrow(M),nrow(c3way),ncol(c3way))
MMM

etc. etc.

Than you can (untested for icc) loop your function as in
apply(MMM,3,somefun)

cheers

On Thu, Mar 29, 2012 at 7:28 AM, Dai, Hongying, <hdai at cmh.edu> wrote:
> Dear R users,
>
> I'm wondering how I can generate an arbitrary number of loops in R.
> For instance, I can generate two "for" loops to get ICC among any two-way combination among 10 variables. Here is the code
>
> n<-10
> for (i in 1:(n-1))
> {
> for (j in (i+1):n)
> {
> icc(cbind(DATA[,i],DATA[,j]))
> }
> }
> If I need three-way combination, then a code with three "for" loops will be:
> n<-10
> for (i in 1:(n-2))
> {
> for (j in (i+1):(n-1))
> {
> for (k in (j+1):n)
> {
> icc(cbind(DATA[,i],DATA[,j],DATA[,k]))
> }
> }
> }
> But how can I write a code if I need all m=2, 3, 4,... loops for arbitrary m-way combinations?
> Thanks!
> Daisy
>
>
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