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

Dai, Hongying, hdai at cmh.edu
Fri Mar 30 03:40:58 CEST 2012

```I figured out how to convert the array to a vector.

library(irr)
M <- matrix(1:50,nc=10)
unlist(combn(10, 2, function(v) icc(M[,v]))[7,])

This code will get all I need. Please ignore my question below. Thanks!

Daisy
-----Original Message-----
From: Dai, Hongying,
Sent: Thursday, March 29, 2012 4:58 PM
To: r-help at r-project.org
Subject: RE: [R] How to create arbitrary number of loops in R

Thanks, ilai and Christian! Both codes are working but I have one more question.

Both codes return results in array format. In my original code, I get icc value from icc(data)\$value and use loop to get icc value vector. Under the array format, how can I extract icc value from the array output and turn it into a vector?

#ilai's code:
library(irr)
M <- matrix(1:50,nc=10)
c2way <- combn(ncol(M),2)
MM <- M[,c2way]
dim(MM) <- c(nrow(M),nrow(c2way),ncol(c2way))
MM
A<-apply(MM,3,icc)  #How can I combine A[[1]]\$value, A[[2]]\$value, ... into a vector?

#Christian's code:
library(irr)
M <- matrix(1:50,nc=10)
combn(10, 2, function(v) icc(M[,v])) #How can I get all values in row 7 as a vector?

Thanks!
Daisy

-----Original Message-----
From: ilaik9 at gmail.com [mailto:ilaik9 at gmail.com] On Behalf Of ilai
Sent: Thursday, March 29, 2012 10:46 AM
To: Dai, Hongying,
Cc: r-help at r-project.org
Subject: Re: [R] How to create arbitrary number of loops in R

On Thu, Mar 29, 2012 at 9:27 AM, ilai <keren at math.montana.edu> wrote:

Oops, sent to fast. A (maybe) clearer solution:

f <- function(x,m){
cmway <- combn(ncol(x),m)
xx <- x[,cmway]
dim(xx) <- c(nrow(x),nrow(cmway),ncol(cmway))
xx
}

f(M,3)
str(sapply(2:4,f,x=M))

And again lapply / apply , or even return icc(xx) in f

Cheers

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