How about? > ave(dat$D, dat$S, FUN=order) [1] 2 1 1 1 2 3 > ave(dat_2$D, dat_2$S, FUN=order) [1] 2 2 1 1 1 3
Note, your answer for the second example is incorrect since row 2 (c, 3) and row 5 (c, 2) are both assigned 2. ------------------------------------- David L Carlson Department of Anthropology Texas A&M University College Station, TX 77840-4352 -----Original Message----- From: R-help [mailto:r-help-boun...@r-project.org] On Behalf Of Tom Wright Sent: Wednesday, February 4, 2015 2:08 PM To: Rui Barradas Cc: r-h...@stat.math.ethz.ch Subject: Re: [R] Still trying to avoid loops Thanks, I was not aware of order(). I did deliberately mess up the order of S. The following example breaks your solution dat_2<-data.frame(S=factor(c('a','c','a','b','c','c')), D=c(5,3,1,3,2,4)) which should give the answer c(2,2,1,1,2,3) Your solution does indicate that sorting the data correctly before starting might solve the problem. On Wed, 2015-02-04 at 19:49 +0000, Rui Barradas 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('a','b','a','c','c','c',levels=c('b','a','c')), > > D=c(1,5,3,2,3,4)) > > > > 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 > > > > ______________________________________________ > > 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. ______________________________________________ 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.