just to satisfy my curiousity, aggregate(bla, list(bla$cat), max) works for me and resulted in
Group.1 x cat v1 v2 v3 v4 1 cat1 5 cat1 0.6337076 0.2887081 0.3629962 0.5328683 2 cat2 10 cat2 0.5519426 0.6076447 0.4593770 0.9632341 3 cat3 11 cat3 0.6094089 0.6152059 0.5670835 0.9084917 4 cat4 8 cat4 0.4772603 0.2149017 0.4534723 0.7824375 5 cat5 9 cat5 0.6582466 0.3150096 0.5512863 1.3524582 6 cat6 12 cat6 0.4632893 0.4498425 0.3926193 0.8023014 so, what didn't work for you, except for the "extra" columns? (taking for granted, that random numbers aren't the same) Am 09.07.2010 16:47, schrieb David Winsemius: > > On Jul 9, 2010, at 10:26 AM, Eik Vettorazzi wrote: > >> you are right. But maybe "aggregate" is close to the desired result? >> >> aggregate(bla, list(bla$cat), max) > > Right. I couldn't get it to work until I removed the first two columns: > > aggregate(bla[,-(1:2)], list(bla$cat), max) > > Then I got pretty much the same dataframe as I would have with : > > as.data.frame(lapply( bla[, -(1:2)], function(x) tapply(x, bla$cat, > max) )) > v1 v2 v3 v4 > cat1 0.4634519 0.5274645 0.6051479 0.7586322 > cat2 0.4062700 0.4282639 0.4443707 0.8419526 > cat3 0.4816403 0.4996033 0.3538144 0.9456385 > cat4 0.6354560 0.3558259 0.3646292 0.1907295 > cat5 0.6663811 0.2154201 0.5059900 0.7573575 > cat6 0.5260832 0.3934063 0.3545962 0.6412563 > > Except that aggregate version returns it with a "Group.1" column of > "cat"s while the other version returned it with the "cat" names in the > rownames. A matter of taste? > -- Eik Vettorazzi Institut für Medizinische Biometrie und Epidemiologie Universitätsklinikum Hamburg-Eppendorf Martinistr. 52 20246 Hamburg T ++49/40/7410-58243 F ++49/40/7410-57790 ______________________________________________ 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.
