If I understand your question, you can try something like this: cor(data.frame(lapply(split(x, x$state), "[", 3)))
On 29/01/2008, Serguei Kaniovski <[EMAIL PROTECTED]> wrote: > Hello, > > I cannot figure out how to use "tapply" to compute the correlation matrix > in the variable "x" between the states? The data is in long format, e.g.: > > state,year,x > Alabama,2001,0.45 > Alabama,2002,0.47 > Alabama,2003,0.48 > Alabama,2004,0.44 > Arizona,2001,0.34 > Arizona,2002,0.32 > Arizona,2003,0.38 > Arizona,2004,0.36 > > Thank you in advance for your help, > Serguei Kaniovski > > ______________________________________________ > 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. > -- Henrique Dallazuanna Curitiba-Paraná-Brasil 25° 25' 40" S 49° 16' 22" O ______________________________________________ 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.