[R] apply & incompatible dimensions error

[Bernzweig, Bruce (Consultant)]

Thanks Benilton,

I know what I want to do, just not sure how to do it using R.  The help
documentation is not very clear.

What I am trying to do is calculate correlations on a row against row
basis:  mat1 row1 x mat2 row1, mat1 row1 x mat2 row2, ... mat1 row1 x
mat2 row-n, mat1 row-n, mat2 row-n

- Bruce

-----Original Message-----
From: Benilton Carvalho [mailto:bcarvalh at jhsph.edu] 
Sent: Tuesday, July 24, 2007 11:31 AM
To: Bernzweig, Bruce (Consultant)
Cc: r-help at stat.math.ethz.ch
Subject: Re: [R] apply & incompatible dimensions error

are you positive that your function is doing what you expect it to do?

it looks like you want something like:

sapply(1:10, function(i) cor(mat1[i,], mat2[i,]))

b

On Jul 24, 2007, at 11:05 AM, Bernzweig, Bruce ((Consultant)) wrote:

> Hi,
>
> I've created the following two matrices (mat1 and mat2) and a function
> (f) to calculate the correlations between the two on a row by row  
> basis.
>
> 	mat1 <- matrix(sample(1:500,50), ncol = 5,
> 		dimnames=list(paste("row", 1:10, sep=""),
> 		paste("col", 1:5, sep="")))
>
> 	mat2 <- matrix(sample(501:1000,50), ncol = 5,
> 		dimnames=list(paste("row", 1:10, sep=""),
> 		paste("col", 1:5, sep="")))
>
> 	f <- function(x,y) cor(x,y)
>
> When the matrices are squares (# rows = # columns) I have no problems.
>
> However, when they are not (as in the example above with 5 columns and
> 10 rows), I get the following error:
>
>> apply(mat1, 1, f, y=mat2)
> Error in cor(x, y, na.method, method == "kendall") :
>         incompatible dimensions
>
> Any help would be appreciated.  Thanks!
>
> - Bruce
>
>
>
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