creating a symmetric matrix
??? A previous answer pointed out ?toeplitz entering
toeplitz
gives
{
if (!is.vector(x))
stop("'x' is not a vector")
n <- length(x)
A <- matrix(0, n, n)
matrix(x[abs(col(A) - row(A)) + 1], n, n)
}
Why reinvent?
-- Bert
On Fri, Sep 7, 2012 at 8:19 AM, David L Carlson <dcarlson at tamu.edu> wrote:
You asked for existing functions, but I was more intrigued by trying to
create one:
symmat <- function(n) {
x <- matrix(1:n, nrow=n, ncol=n)
abs(x-col(x))+1
}
symmat(4)
[,1] [,2] [,3] [,4] [1,] 1 2 3 4 [2,] 2 1 2 3 [3,] 3 2 1 2 [4,] 4 3 2 1 ---------------------------------------------- David L Carlson Associate Professor of Anthropology Texas A&M University College Station, TX 77843-4352
-----Original Message----- From: r-help-bounces at r-project.org [mailto:r-help-bounces at r- project.org] On Behalf Of Erin Hodgess Sent: Thursday, September 06, 2012 8:11 PM To: R help Subject: [R] creating a symmetric matrix Dear R People: Suppose I have the following: x <- 1:4 And I want to create the following matrix: 1 2 3 4 2 1 2 3 3 2 1 2 4 3 2 1 Is there a function in place for this, please? I looked at symMatrix in micEcon and some of the items in Matrix, but they didn't quite do it. I can put together something quickly, of course, but it seems likely that this would exist. Thanks, Erin -- Erin Hodgess Associate Professor Department of Computer and Mathematical Sciences University of Houston - Downtown mailto: erinm.hodgess at gmail.com
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______________________________________________ R-help at r-project.org 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.
Bert Gunter Genentech Nonclinical Biostatistics Internal Contact Info: Phone: 467-7374 Website: http://pharmadevelopment.roche.com/index/pdb/pdb-functional-groups/pdb-biostatistics/pdb-ncb-home.htm