Re: [R] Selective subsetting
A=matrix(1:9,3) A[lower.tri(A)] b On Nov 10, 2006, at 4:50 PM, Davendra Sohal wrote: Hi all, Here's an interesting (for me, at least!) problem I came across: I have a correlation matrix, let's say with 6 variables, A to F, as column headings and the same 6 as row headings. The matrix is filled with correlation coefficients. Therefore, the diagonal is all 1's, and each of the two triangles formed by the diagonal has the same 15 correlation coefficients. I need to extract these 15 coefficients from this. I don't want the 1's and I don't want redundant values. I tried converting the matrix to a list, using c(m) and then I'm stuck. Does something like b = a[x, x+1:n] exist in R? SAS will do it. x can be looped to go from 1 to n (n here is 6, of course) and it will select the required values, but I cannot make it work. Please help. Many thanks, -DS. [[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. __ 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] Selective subsetting
try this: cor.mat - cor(iris[1:4]) cor.mat[lower.tri(cor.mat)] I hope it helps. Best, Dimitris Dimitris Rizopoulos Ph.D. Student Biostatistical Centre School of Public Health Catholic University of Leuven Address: Kapucijnenvoer 35, Leuven, Belgium Tel: +32/(0)16/336899 Fax: +32/(0)16/337015 Web: http://med.kuleuven.be/biostat/ http://www.student.kuleuven.be/~m0390867/dimitris.htm Quoting Davendra Sohal [EMAIL PROTECTED]: Hi all, Here's an interesting (for me, at least!) problem I came across: I have a correlation matrix, let's say with 6 variables, A to F, as column headings and the same 6 as row headings. The matrix is filled with correlation coefficients. Therefore, the diagonal is all 1's, and each of the two triangles formed by the diagonal has the same 15 correlation coefficients. I need to extract these 15 coefficients from this. I don't want the 1's and I don't want redundant values. I tried converting the matrix to a list, using c(m) and then I'm stuck. Does something like b = a[x, x+1:n] exist in R? SAS will do it. x can be looped to go from 1 to n (n here is 6, of course) and it will select the required values, but I cannot make it work. Please help. Many thanks, -DS. [[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. Disclaimer: http://www.kuleuven.be/cwis/email_disclaimer.htm __ 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] Selective subsetting
Look at the functions tril() and triu() in the Matrix package Regards Francisco Davendra Sohal wrote: Hi all, Here's an interesting (for me, at least!) problem I came across: I have a correlation matrix, let's say with 6 variables, A to F, as column headings and the same 6 as row headings. The matrix is filled with correlation coefficients. Therefore, the diagonal is all 1's, and each of the two triangles formed by the diagonal has the same 15 correlation coefficients. I need to extract these 15 coefficients from this. I don't want the 1's and I don't want redundant values. I tried converting the matrix to a list, using c(m) and then I'm stuck. Does something like b = a[x, x+1:n] exist in R? SAS will do it. x can be looped to go from 1 to n (n here is 6, of course) and it will select the required values, but I cannot make it work. Please help. Many thanks, -DS. [[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. -- Dr. Francisco J. Zagmutt College of Veterinary Medicine and Biomedical Sciences Colorado State University __ 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.
