Hi Val, I think you answered your own question: by(dat$wt,dat[,c("Sex","Year")],mean)
Jim On Tue, Nov 2, 2021 at 8:09 AM 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. ______________________________________________ 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.