No problem with disguise, I'm looking for pretty. On Wed, 2015-02-04 at 12:06 -0800, Bert Gunter wrote: > tapply() (of which by() is essentially a wrapper) **is** a (disguised) > loop (at the R level, of course). > > Cheers, > Bert > > > > Bert Gunter > Genentech Nonclinical Biostatistics > (650) 467-7374 > > "Data is not information. Information is not knowledge. And knowledge > is certainly not wisdom." > Clifford Stoll > > > > > On Wed, Feb 4, 2015 at 11:49 AM, Rui Barradas <[email protected]> wrote: > > Hello, > > > > Aren't the levels of your example wrong? If the levels are > > levels=c('a','b','c'), not c('b', 'a', 'c'), then the following will do the > > job. > > > > unname(unlist(tapply(dat$D, dat$S, order))) > > > > > > Hope this helps, > > > > Rui Barradas > > > > Em 04-02-2015 19:34, Tom Wright escreveu: > >> > >> Given a dataframe: > >> > >> dat<-data.frame(S=factor(c(rep('a',2),rep('b',1),rep('c',3)),levels=c('b','a','c')), > >> D=c(5,1,3,2,3,4)) > >> > >> where S is a subject identifier and D a visit (actually a date in my > >> real dataset). I would like to generate another column giving the visit > >> number > >> > >> R=c(2,1,1,1,2,3) > >> > >> My current solution uses nested loops and is slow and ugly. I've looked > >> at by() but can't see how to keep the order of R correct. > >> > >> Thanks, > >> Tom > >> > >> ______________________________________________ > >> [email protected] 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. > >> > > > > ______________________________________________ > > [email protected] 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.
______________________________________________ [email protected] 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.
