Hi
other approach is to use embed
embed(c(rhsel,rhsel),length(rhsel))[-1,]
which is a little bit quicker
rhsel-rnorm(1000)
n - length(rhsel)
system.time({
i - sapply(1:n, function(i) (1:n - i)%%n + 1)
x2-matrix(rhsel[i], n, n)
})
system.time(x1-embed(c(rhsel,rhsel),length(rhsel))[-1,])
all.equal(x1,x2)
HTH
Petr
On 21 Sep 2006 at 14:53, Sundar Dorai-Raj wrote:
Date sent: Thu, 21 Sep 2006 14:53:52 -0500
From: Sundar Dorai-Raj [EMAIL PROTECTED]
Organization: PDF Solutions, Inc.
To: kone [EMAIL PROTECTED]
Copies to: r-help@stat.math.ethz.ch
Subject:Re: [R] Matrix from a vector?
kone said the following on 9/21/2006 2:30 PM:
Hi,
Is there some function, which generates this kind of n x n -matrix
from a vector?
rhset
[1] 1792 256 13312 512 1024 2048 8192 4096
m=matrix(nrow=length(rhset),ncol=length(rhset))
for(i in 1:length(rhset))
+ {
+ m[,i]=rhset
+ rhset=c(rhset[length(rhset)], rhset[2:length(rhset)-1])
+ }
m
[,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8]
[1,] 1792 4096 8192 2048 1024 512 13312 256
[2,] 256 1792 4096 8192 2048 1024 512 13312
[3,] 13312 256 1792 4096 8192 2048 1024 512
[4,] 512 13312 256 1792 4096 8192 2048 1024
[5,] 1024 512 13312 256 1792 4096 8192 2048
[6,] 2048 1024 512 13312 256 1792 4096 8192
[7,] 8192 2048 1024 512 13312 256 1792 4096
[8,] 4096 8192 2048 1024 512 13312 256 1792
Atte Tenkanen
University of Turku, Finland
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Does this work for you?
rhsel - c(1792, 256, 13312, 512, 1024, 2048, 8192, 4096)
n - length(rhsel)
i - sapply(1:n, function(i) (1:n - i)%%n + 1)
matrix(rhsel[i], n, n)
HTH,
--sundar
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PLEASE do read the posting guide
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minimal, self-contained, reproducible code.
Petr Pikal
[EMAIL PROTECTED]
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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.
