[R] manipulating longitudinal data in r

[Michael Dewey]

At 17:13 18/11/2012, Jeff Newmiller wrote:
>Michael, this comment doesn't seem appropriate to the question, 
>since the sample data is a ragged array that requires the addition 
>of NAs to fit into a wide format.

It does now but we do not know whether that was how it started life. 
My remarks were intended as a general comment, not necessarily a 
solution to the OP's specific problem.

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>Sent from my phone. Please excuse my brevity.
>
>Michael Dewey <info at aghmed.fsnet.co.uk> wrote:
>
> >At 08:56 17/11/2012, Kemi Racheal wrote:
> >>Dear list member,
> >>
> >>I have the following data example
> >>ke <- data.frame(patid=c(1,1,1,2,3,3),a=c(1,2,2,1,1,2))
> >>
> >>I want to add another variable b, such that the max of 'a' by id is
> >returned
> >>i.e data ke becomes
> >>ke <-
> >data.frame(patid=c(1,1,1,2,3,3),a=c(1,2,2,1,1,2),b=c(2,2,2,1,2,2))
> >>
> >>Any help will be appreciated.
> >
> >Dear Kemi
> >It is often easier to do some sorts of manipulations on the wide
> >format of the data. I appreciate that you can always do it both ways.
> >
> >
> >>Oluwakemi
> >>
> >>
> >>         [[alternative HTML version deleted]]
> >
> >Michael Dewey
> >info at aghmed.fsnet.co.uk
> >http://www.aghmed.fsnet.co.uk/home.html
> >
> >______________________________________________
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> >PLEASE do read the posting guide
> >http://www.R-project.org/posting-guide.html
> >and provide commented, minimal, self-contained, reproducible code.

Michael Dewey
info at aghmed.fsnet.co.uk
http://www.aghmed.fsnet.co.uk/home.html