Re: [R] an easy way to construct this special matirx
It was pointed out that the required matrix may not be square and the superdiagonal was missing in my prior post. Here is a revision: r <- 2; nr <- 4; nc <- 5 # test data x <- matrix(nr = nr, nc = nc) x <- row(x) - col(x) + 1 (x >= 0) * r ^ x On 8/16/07, Gabor Grothendieck <[EMAIL PROTECTED]> wrote: > Here are two solutions. In the first lo has TRUE on the lower diagonal > and diagonal. Then we compute the exponents, multiplying by lo to zero > out the upper triangle. In the second rn is a matrix of row numbers > and rn >= t(rn) is the same as lo in the first solution. > > r <- 2; n <- 5 # test data > > lo <- lower.tri(diag(n), diag = TRUE) > lo * r ^ (row(lo) - col(lo) + 1) > > Here is another one: > > rn <- row(diag(n)) > (rn >= t(rn)) * r ^ (rn - t(rn) + 1) > > On 8/15/07, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote: > > Hi, > > Sorry if this is a repost. I searched but found no results. > > I am wondering if it is an easy way to construct the following matrix: > > > > r 1 0 00 > > r^2 r 1 00 > > r^3 r^2 r 10 > > r^4 r^3 r^2 r1 > > > > where r could be any number. Thanks. > > Wen > __ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Re: [R] an easy way to construct this special matirx
Hi Gabor, I am glad to see your answer,which gives a hope to resove this question in an easy way. I replied to this question in a more complex way before seeing your answer. However,I think your code needs some revision, because the original matrix is not a diagonal matrix. It has 4 rows and 5 columns.Looking forward to your revised codes. Best regards, On Thu, Aug 16, 2007 20:22, Gabor Grothendieck wrote: > Here are two solutions. In the first lo has TRUE on the lower > diagonal > and diagonal. Then we compute the exponents, multiplying by lo to > zero > out the upper triangle. In the second rn is a matrix of row numbers > and rn >= t(rn) is the same as lo in the first solution. > > r <- 2; n <- 5 # test data > > lo <- lower.tri(diag(n), diag = TRUE) > lo * r ^ (row(lo) - col(lo) + 1) > > Here is another one: > > rn <- row(diag(n)) > (rn >= t(rn)) * r ^ (rn - t(rn) + 1) > > On 8/15/07, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote: >> Hi, >> Sorry if this is a repost. I searched but found no results. >> I am wondering if it is an easy way to construct the following >> matrix: >> >> r 1 0 00 >> r^2 r 1 00 >> r^3 r^2 r 10 >> r^4 r^3 r^2 r1 >> >> where r could be any number. Thanks. >> Wen > > __ > R-help@stat.math.ethz.ch mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide > http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. > -- De-Jian Zhao Institute of Zoology,Chinese Academy of Sciences +86-10-64807217 [EMAIL PROTECTED] __ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Re: [R] an easy way to construct this special matirx
Hi wen,
I don't think it is easy to construct this matrix in a simple way. I
tried and found a way to do it. Try the following codes:
i<-1:4
j<-5
aa<-matrix(0,4,5)
for (j in 1:5){aa[i,j]<-(i+1-j)}
r<-4 #r could be any number
bb<-r^aa
bb[aa<0]=0
bb
The matrix bb is what you want. Furthermore,I packaged this process
into a function called mtrx as below:
mtrx<-function(row,clm,r){
i<-1:row
j<-clm
aa<-matrix(row*clm,row,clm)
for (j in 1:clm){aa[i,j]<-(i+1-j)}
#r could be any number
bb<-r^aa
bb[aa<0]=0
bb
}
Now you can use the function to produce the matrix.The
above-mentioned matrix is mtrx(4,5,4)
Dejian Zhao
On Thu, Aug 16, 2007 11:10, [EMAIL PROTECTED] wrote:
> Hi,
> Sorry if this is a repost. I searched but found no results.
> I am wondering if it is an easy way to construct the following
> matrix:
>
> r 1 0 00
> r^2 r 1 00
> r^3 r^2 r 10
> r^4 r^3 r^2 r1
>
> where r could be any number. Thanks.
> Wen
> [[alternative HTML version deleted]]
>
> __
> R-help@stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
--
De-Jian Zhao
Institute of Zoology,Chinese Academy of Sciences
+86-10-64807217
[EMAIL PROTECTED]
__
R-help@stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
Re: [R] an easy way to construct this special matirx
Here are two solutions. In the first lo has TRUE on the lower diagonal and diagonal. Then we compute the exponents, multiplying by lo to zero out the upper triangle. In the second rn is a matrix of row numbers and rn >= t(rn) is the same as lo in the first solution. r <- 2; n <- 5 # test data lo <- lower.tri(diag(n), diag = TRUE) lo * r ^ (row(lo) - col(lo) + 1) Here is another one: rn <- row(diag(n)) (rn >= t(rn)) * r ^ (rn - t(rn) + 1) On 8/15/07, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote: > Hi, > Sorry if this is a repost. I searched but found no results. > I am wondering if it is an easy way to construct the following matrix: > > r 1 0 00 > r^2 r 1 00 > r^3 r^2 r 10 > r^4 r^3 r^2 r1 > > where r could be any number. Thanks. > Wen __ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Re: [R] an easy way to construct this special matirx
?toeplitz ?lower.tri since it is the lower triangle of a Toeplitz matrix (or drop the top row) r <- 0.95 R <- toeplitz(r^(0:4)) R[upper.tri(R)] <- 0 R[-1,] On Thu, 16 Aug 2007, [EMAIL PROTECTED] wrote: > Hi, > Sorry if this is a repost. I searched but found no results. > I am wondering if it is an easy way to construct the following matrix: > > r 1 0 00 > r^2 r 1 00 > r^3 r^2 r 10 > r^4 r^3 r^2 r1 > > where r could be any number. Thanks. > Wen -- Brian D. Ripley, [EMAIL PROTECTED] Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UKFax: +44 1865 272595 __ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Re: [R] an easy way to construct this special matirx
On 16-Aug-07 03:10:17, [EMAIL PROTECTED] wrote: > Hi, > Sorry if this is a repost. I searched but found no results. > I am wondering if it is an easy way to construct the following matrix: > > r 1000 > r^2 r100 > r^3 r^2 r10 > r^4 r^3 r^2 r1 > > where r could be any number. Thanks. > Wen I dare say there's an even simpler way (and I feel certain someone will post one ... ); but (example): r<-0.1 r1<-r^((-3):0); r2<-r^(3:0) R<-r1%*%t(r2) R ## [,1] [,2] [,3] [,4] ##[1,] 1.000 10.00 100.0 1000 ##[2,] 0.100 1.00 10.0 100 ##[3,] 0.010 0.10 1.0 10 ##[4,] 0.001 0.01 0.11 R[upper.tri(R)]<-0 R ## [,1] [,2] [,3] [,4] ##[1,] 1.000 0.00 0.00 ##[2,] 0.100 1.00 0.00 ##[3,] 0.010 0.10 1.00 ##[4,] 0.001 0.01 0.11 Best wishes, Ted. E-Mail: (Ted Harding) <[EMAIL PROTECTED]> Fax-to-email: +44 (0)870 094 0861 Date: 16-Aug-07 Time: 09:37:28 -- XFMail -- __ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
[R] an easy way to construct this special matirx
Hi, Sorry if this is a repost. I searched but found no results. I am wondering if it is an easy way to construct the following matrix: r 1 0 00 r^2 r 1 00 r^3 r^2 r 10 r^4 r^3 r^2 r1 where r could be any number. Thanks. Wen [[alternative HTML version deleted]] __ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
