R help - Mar 2012 - How to create arbitrary number of loops in R

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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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
>
>
> ________________________________
> Electronic mail from Children's Mercy Hospitals and Clinics. This
communication is intended only for the use of the addressee. It may contain
information that is privileged or confidential under applicable law. If you are
not the intended recipient or the agent of the recipient, you are hereby
notified that any dissemination, copy or disclosure of this communication is
strictly prohibited. If you have received this communication in error, please
immediately forward the message to Children's Mercy Hospital's
Information Security Officer via return electronic mail at
informationsecurityofficer at cmh.edu and expunge this communication without
making any copies. Thank you for your cooperation.
>
> ? ? ? ?[[alternative HTML version deleted]]
>
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