Try this:
dat$sequence <- as.vector(unlist(lapply( aggregate(dat$ID, by=list(x),
FUN=length)$x, FUN=function(x){seq(1, x))))
dat0 <- dat[dat$sequence==1, ]

HTH, X


On Sat, Feb 23, 2013 at 1:07 PM, Rui Barradas <ruipbarradas@sapo.pt> wrote:

> Hello,
>
> You can use ?aggregate and ?head to do what you want. Try the following.
>
>
>
> dat <- read.table(text="
>
> ID    COMPL  SEX  HEREDITY
> 1    0      1      2
> 1    0      1      2
> 1    3      1      2
> 2    0      0      1
> 2    1      0      1
> 2    2      0      1
> 2    2      0      1
> 3    0      0      1
> 3    0      0      1
> 3    0      0      1
> 3    0      0      1
> 3    2      0      1
> 4    0      1      2
> 4    0      1      2
> ", header = TRUE)
>
> aggregate(. ~ ID, data = subset(dat, COMPL != 0), head, 1)
>
>
> Hope this helps,
>
> Rui Barradas
>
> Em 23-02-2013 14:28, Tasnuva Tabassum escreveu:
>
>  I have a longitudinal competing risk data of the form:
>>
>> ID    COMPL  SEX   HEREDITY
>> 1     0       1      2
>> 1     0       1      2
>> 1     3       1      2
>> 2     0       0      1
>> 2     1       0      1
>> 2     2       0      1
>> 2     2       0      1
>> 3     0       0      1
>> 3     0       0      1
>> 3     0       0      1
>> 3     0       0      1
>> 3     2       0      1
>> 4     0       1      2
>> 4     0       1      2.
>>
>> Where, COMPL= health complication of diabetic patients which has value
>> labels   as  0= no complication,1=coronary heart disease, 2=retinopathy,
>> 3=
>> nephropathy.
>>
>>
>> I want to select only the first complication that occurred to each
>> patient.
>> What R function can I use?
>>
>>         [[alternative HTML version deleted]]
>>
>> ______________________________**________________
>> R-help@r-project.org mailing list
>> https://stat.ethz.ch/mailman/**listinfo/r-help<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.
>>
>>
> ______________________________**________________
> R-help@r-project.org mailing list
> https://stat.ethz.ch/mailman/**listinfo/r-help<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.
>



-- 
==============================
Xiaogang Su, Ph.D.
Associate Professor & Statistician
School of Nursing, University of Alabama
Birmingham, AL 35294-1210
(205) 934-2355 [Office]
xgsu@uab.edu
xiaogangsu@gmail.com
https://sites.google.com/site/xgsu00/

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