x<-c(1,1,1,1,1,2,2,2,2,2) y<-rnorm(10) z<-y+rnorm(10) by(data.frame(y,z),factor(x),cor)
hth, Daniel jfdawson wrote: > > I'm hoping there is a simple answer to this - it seems that there should > be, but I can't figure it out. > > I have a matrix/data frame with three variables of interest - V1, V2, V3. > One, V1, is a factor with x levels (x may be a large number); I want to > calculate the correlation between the other two (i.e. cor(V2,V3)) for > each level, and store it as a vector of length x. > > I should think this should be possible using a function like tapply, but I > cannot work out what the syntax would be - everything I have tried > produces either an error, or just repeats the correlations between V2 & V3 > on the whole matrix. > > Could anyone suggest what I should be doing? > > Many thanks, > Jeremy > -- View this message in context: http://r.789695.n4.nabble.com/Correlations-by-subgroups-tp3599548p3600553.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ 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.
