one option is the following:
do.call(rbind, lapply(split(tox, tox$id), function (x) {
if (any(ind <- x$event == 1))
x[which(ind)[1], ]
else
x[nrow(x), ]
}))
I hope it helps.
Best,
Dimitris
----
Dimitris Rizopoulos
Ph.D. Student
Biostatistical Centre
School of Public Health
Catholic University of Leuven
Address: Kapucijnenvoer 35, Leuven, Belgium
Tel: +32/(0)16/336899
Fax: +32/(0)16/337015
Web: http://med.kuleuven.be/biostat/
http://www.student.kuleuven.be/~m0390867/dimitris.htm
----- Original Message -----
From: "Williams Scott" <Scott.Williams at petermac.org>
To: <r-help at stat.math.ethz.ch>
Sent: Monday, April 23, 2007 10:14 AM
Subject: [R] data recoding problem
> Hi R experts,
>
> I have a data recoding problem I cant get my head around - I am not
> that
> great at the subsetting syntax. I have a dataset of longitudinal
> toxicity data (for multistate modelling) for which I want to also
> want
> to do a simple Kaplan-Meier curve of the time to first toxic event.
>
> The data for 2 cases presently looks like this (one with an event,
> the
> other without), with id representing each person on study, and
> follow-up
> time and status:
>
>
>> tox
>
> id t event
>
> PMC011 0.000 0
> PMC011 3.154 0
> PMC011 5.914 0
> PMC011 12.353 0
> PMC011 18.103 1
> PMC011 24.312 0
> PMC011 30.029 0
> PMC011 47.967 0
> PMC011 96.953 0
> PMC016 0.000 0
> PMC016 3.943 0
> PMC016 5.782 0
> PMC016 11.762 0
> PMC016 17.741 0
> PMC016 23.951 0
> PMC016 28.353 0
> PMC016 44.747 0
> PMC016 89.692 0
>
> So what I need is an output in the same column format, containing
> each
> of the unique values of id:
>
> PMC011 18.103 1
> PMC016 89.692 0
>
> In my head, I would do this by looking at each unique value of id
> (each
> unique case), look down the event data of each of these cases - if
> there
> is no event (event==0), then I would go to the time column (t) and
> find
> the max value and paste this time along with a 0 for event. If there
> were an event, I would then need to find the minimum time associated
> with an event to paste across with the event marker. I am sure
> someone
> out there can point me in the right direction to do this without
> tedious
> and slow loops. Any help greatly appreciated.
>
> Cheers
>
> Scott
> _____________________________
>
> Dr. Scott Williams
>
> MBBS BScMed FRANZCR
>
> Radiation Oncologist
>
> Peter MacCallum Cancer Centre
>
> Melbourne, Australia
>
> ph +61 3 9656 1111
>
> fax +61 3 9656 1424
>
> scott.williams at petermac.org
>
> ______________________________________________
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> and provide commented, minimal, self-contained, reproducible code.
>
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