Check the following example for by(): require(stats) attach(warpbreaks) by(warpbreaks, tension, function(x) lm(breaks ~ wool, data = x))
or just type: example(by) b On Jul 19, 2007, at 1:18 PM, Hongmei Jia wrote: > > Dear All, > > I'm trying to do 'glm' analysis by groups just like in SAS you use "by > variable". I don't know how to do it in R, anyone can help with > this? > i.e. > > group line rep value > 1 1 1 0.2 > 1 1 2 0.3 > 1 1 3 0.23 > 1 2 1 0.2 > 1 2 2 0.3 > 1 2 3 0.23 > 2 1 1 0.2 > 2 1 2 0.3 > 2 1 3 0.23 > 2 2 1 0.2 > 2 2 2 0.3 > 2 2 3 0.23 > > in SAS we say: > model value=line rep; > by group; > > How can I do this in R? > > Thanks, > > Hongmei Jia > > ______________________________________________ > R-help@stat.math.ethz.ch 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@stat.math.ethz.ch 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.