I seem to be suffering from the same problem (the Friday one, not the cor one)
Have a look at http://stats.stackexchange.com/questions/4040/r-compute-correlation-by-group for something that looks like it will work John Kane Kingston ON Canada > -----Original Message----- > From: [email protected] > Sent: Fri, 8 Feb 2013 08:33:45 -0800 (PST) > To: [email protected] > Subject: [R] aggregation-type question > > I seem to have a Friday afternoon block and can't see the easiest way of > doing this. > > Given a data frame like: > > dat <- data.frame(x = runif(100), y = runif(100), group = > rep(letters[1:10], > each = 10)) >> head(dat) > x y group > 1 0.876751503 0.6518345 a > 2 0.627067150 0.8801790 a > 3 0.632465192 0.1768305 a > 4 0.060359554 0.8835652 a > 5 0.675868776 0.7721177 a > 6 0.008465241 0.5046486 a > > I want to work out cor(x, y) by group, so in this case ending up with 10 > correlation coefficients by group. > > I'm not seeing a straightforward solution and I'd appreciate your help. > > Thanks > > David > > > > -- > View this message in context: > http://r.789695.n4.nabble.com/aggregation-type-question-tp4657966.html > Sent from the R help mailing list archive at Nabble.com. > > ______________________________________________ > [email protected] 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. ____________________________________________________________ FREE 3D EARTH SCREENSAVER - Watch the Earth right on your desktop! ______________________________________________ [email protected] 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.
