[R] Correlations by subgroups

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

Re: [R] Correlations by subgroups

I have to confess that plyr has made me lazy about remembering tapply, by, aggregate et al., so I'm no help there. But if you want to use plyr it's just ddply(dat, .(V1), summarize, cor.v2.v3 = cor(V2, V3)) Best, Ista On Wed, Jun 15, 2011 at 10:31 AM, jfdawson j.f.daw...@aston.ac.uk wrote: I'm

Re: [R] Correlations by subgroups

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,

Re: [R] Correlations by subgroups

Many thanks - this is exactly what I was hoping for. Very helpful! Best wishes, Jeremy On 15 Jun 2011, at 21:22, Ista Zahn-2 [via R] wrote: I have to confess that plyr has made me lazy about remembering tapply, by, aggregate et al., so I'm no help there. But if you want to use plyr it's just

Re: [R] Correlations by subgroups

Many thanks - this is very helpful indeed! Best wishes, Jeremy On 15 Jun 2011, at 21:58, Daniel Malter [via R] wrote: 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