Is this what you want:

> x <- read.table(textConnection("CAO0337134      05/09/95
+ CAO0337134      27/09/05
+ CAO0347741      10/10/04
+ CAO0347741      12/10/04
+ CAO0367128      11/07/05
+ CAO0367128      12/07/05
+ CAO0367128      14/07/05
+ CAO0367128      19/09/97
+ CAO0367128      20/09/97
+ CAO0374110      14/11/89
+ CAO0374110      17/11/89
+ CAO0374779      01/10/99
+ CAO0374779      28/09/99
+ CAO0374779      29/09/99"), as.is=TRUE)
> closeAllConnections()
> x.l <- lapply(split(x, x$V1), function(a) c(a$V2))
> # find longest length
> max.len <- max(sapply(x.l, length))
> # pad and rbind
> do.call(rbind, lapply(x.l, function(a){
+     c(a, rep(NA, max.len - length(a)))
+ }))
           [,1]       [,2]       [,3]       [,4]       [,5]
CAO0337134 "05/09/95" "27/09/05" NA         NA         NA
CAO0347741 "10/10/04" "12/10/04" NA         NA         NA
CAO0367128 "11/07/05" "12/07/05" "14/07/05" "19/09/97" "20/09/97"
CAO0374110 "14/11/89" "17/11/89" NA         NA         NA
CAO0374779 "01/10/99" "28/09/99" "29/09/99" NA         NA
>
>


On Sat, Feb 20, 2010 at 7:26 AM, Newbie19_02 <nvanzuydam@gmail.com> wrote:

>
> Hi there,
>
> I think I'm struggling with a fairly simple problem but can't seem to solve
> it.  I have multiple observations for one unique identifier.  Ultimately I
> want to end up with one line per identifier with multiple observations in
> rows. I'm really stuck any help would be really appreciated.
>
>
> CAO0337134      05/09/95
> CAO0337134      27/09/05
> CAO0347741      10/10/04
> CAO0347741      12/10/04
> CAO0367128      11/07/05
> CAO0367128      12/07/05
> CAO0367128      14/07/05
> CAO0367128      19/09/97
> CAO0367128      20/09/97
> CAO0374110      14/11/89
> CAO0374110      17/11/89
> CAO0374779      01/10/99
> CAO0374779      28/09/99
> CAO0374779      29/09/99
>
> Thanks
> Natalie
> --
> View this message in context:
> http://n4.nabble.com/Rearranging-a-data-frame-for-multiple-observations-tp1562780p1562780.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> 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<http://www.r-project.org/posting-guide.html>
> and provide commented, minimal, self-contained, reproducible code.
>



-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390

What is the problem that you are trying to solve?

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