[R] Still trying to avoid loops

[Tom Wright]

Of course you are correct the second answer should be
 c(2,2,1,1,1,3)

Thanks everyone.

On Wed, 2015-02-04 at 20:53 +0000, David L Carlson wrote:
> 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-bounces at r-project.org] On Behalf Of Tom Wright
> Sent: Wednesday, February 4, 2015 2:08 PM
> To: Rui Barradas
> Cc: r-help at 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 at 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 at 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.