I would usually use 'tapply'. It splits an object into groups, performs some function on each group, and then (optionally) converts the input to something simpler. For example:
tapply(dat$wt, dat$Year, mean) # mean by Year tapply(dat$wt, dat$Sex , mean) # mean by Sex tapply(dat$wt, list(dat$Year, dat$Sex), mean) # mean by Year and Sex The documentation ?tapply has many more details about how this works, but that's the basics at least. I hope this helps! On Mon, Nov 1, 2021 at 5:09 PM Val <valkr...@gmail.com> wrote: > Hi All, > > How can I generate mean by group. The sample data looks like as follow, > dat<-read.table(text="Year Sex wt > 2001 M 15 > 2001 M 14 > 2001 M 16 > 2001 F 12 > 2001 F 11 > 2001 F 13 > 2002 M 14 > 2002 M 18 > 2002 M 17 > 2002 F 11 > 2002 F 15 > 2002 F 14 > 2003 M 18 > 2003 M 13 > 2003 M 14 > 2003 F 15 > 2003 F 10 > 2003 F 11 ",header=TRUE) > > The desired output is, > M F > 2001 15 12 > 2002 16.33 13.33 > 2003 15 12 > > Thank you, > > ______________________________________________ > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > 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. > [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.
