# Re: [R] loop problem

From: TEMPL Matthias <Matthias.Templ_at_statistik.gv.at>
Date: Tue 06 Dec 2005 - 03:00:09 EST

Hello Frank

> Hi,
> Here is my problem. Say I have two matrices,
>
> Matrix A:
>
> a b c
> 4 5 2
> 3 2 1
> 4 5 6
>
> Matrix B:
> d e f g h
> 3 4 5 2 1
> 2 3 7 8 6
> 8 5 1 3 4

Please produce a reproducable example, like

A <- matrix(rnorm(9),ncol=3)
B <- matrix(rnorm(15), ncol=5)

Here is just the loop for you:

n <- 0

z <- vector() # or z <- 1:(dim(A)+dim(B)) for(i in 1:dim(A)){
for( j in 1:dim(B) ){
n <- n + 1
z[n] <- cor(A[,i], B[,j])
}
}

I hope this helps,
Matthias

>
> I would like to correlate vector a of matrix A with with
> vectors d,e,f,g,h of matrix "B" and save the p-values (or
> some type of statistic) in a seperate result vector, say z.
> Then, I would like to repeat this process for vector b and
> vector c of matrix A. In the present example, vector z would
> end up containg 15 elements.
> I tried a few double loops, but was not successful in saving
> the results in a vector. I was only able to print them with
> the "print" or "cat" command, but could not turn the print or
> cat results into an accessible object.
>
> Help would be appreciated.
> Thank you,
> Frank.
>
> --
>
> or over the web
>
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