Re: [R] how ot replace the diagonal of a matrix

From: jim holtman <jholtman_at_gmail.com>
Date: Tue 03 Oct 2006 - 21:12:06 GMT

try:

> mps <- matrix(rep(.4, 3*3), nrow=3, byrow=TRUE)
> idx <- diag(3)
> mps

     [,1] [,2] [,3]

[1,]  0.4  0.4  0.4
[2,]  0.4  0.4  0.4
[3,]  0.4  0.4  0.4

> idx
[,1] [,2] [,3] [1,] 1 0 0

[2,] 0 1 0

[3,] 0 0 1
> mps[idx == 1] <- rep(.6,3)
>
> mps

     [,1] [,2] [,3]

[1,]  0.6  0.4  0.4
[2,]  0.4  0.6  0.4
[3,]  0.4  0.4  0.6

>

On 10/3/06, roger bos <roger.bos@gmail.com> wrote:
> Dear useRs,
>
> Trying to replace the diagonal of a matrix is not working for me. I
> want a matrix with .6 on the diag and .4 elsewhere. The following
> code looks like it should work--when I lookk at mps and idx they look
> how I want them too--but it only replaces the first element, not each
> element on the diagonal.
>
> mps <- matrix(rep(.4, 3*3), nrow=n, byrow=TRUE)
> idx <- diag(3)
> mps
> idx
> mps[idx] <- rep(.6,3)
>
> I also tried something along the lines of diag(mps=.6, ...) but it
> didn't know what mps was.
>
> Thanks,
>
> Roger
>
> ______________________________________________
> R-help@stat.math.ethz.ch mailing list
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> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>

-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390

What is the problem you are trying to solve?

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Received on Wed Oct 04 07:27:20 2006

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