Hi, May be this also helps: library(data.table) dt1<- data.table(dat) dt1[,cor(x,y),by=g] # g V1 #1: A -0.05643063 #2: B 0.16465040 dt1[,cor(x,y),by=g]$V1 #[1] -0.05643063 0.16465040
A.K. ----- Original Message ----- From: David Carlson <dcarl...@tamu.edu> To: 'Jannis' <bt_jan...@yahoo.de>; 'r-help' <r-help@r-project.org> Cc: Sent: Thursday, June 27, 2013 3:22 PM Subject: Re: [R] multivariate version of aggregate You can pass a matrix to by() > set.seed(42) > dat <- data.frame(x=runif(50)*20, y=runif(50)*20, g=rep(LETTERS[1:2], each=25)) > as.vector(by(dat[,1:2], dat$g, function(x) cor(x)[1,2])) [1] -0.05643063 0.16465040 ------------------------------------- David L Carlson Associate Professor of Anthropology Texas A&M University College Station, TX 77840-4352 -----Original Message----- From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On Behalf Of Jannis Sent: Thursday, June 27, 2013 12:27 PM To: r-help Subject: [R] multivariate version of aggregate Dear List members, i am seeking a multivariate version of aggregate. I want to compute, fro example the correlation between subsets of two vectors. In aggregate, i can only supply one vector with indices for subsets. Is there ready function for this or do i need to program my own? Cheers Jannis ______________________________________________ R-help@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. ______________________________________________ R-help@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. ______________________________________________ R-help@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.
