?aggregate tt <- matrix(c(rnorm(10), 1,1,2,2,1,3,3,3,3,2), ncol=2)) aggregate(t[,1], by=list(t[,2]), mean) should work
--- Ng Stanley <[EMAIL PROTECTED]> wrote: > Hi, > > I have a two columns data, the first column are > values, and second column > are the groups. For this example, there are 3 groups > 1,2,3. > > How can I manipulate the values in the first column > according to groups, say > I would like to find mean, sum, and standard > deviation for the different > groups ? How do I plot data according to groups ? > > > t <- matrix(c(rnorm(10), 1,1,2,2,1,3,3,3,3,2), > ncol=2) > > [[alternative HTML version deleted]] > > ______________________________________________ > 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.
