[R] Splitting a dataframe at the results of tapply

[Dimitris Rizopoulos]

try this:

dat <- data.frame(Id, Noise, Height)
##############
dat <- dat[order(dat$Id), ]
ind <- unlist(tapply(dat$Noise, dat$Id, function(x) x == max(x)))
dat[ind, ]
dat[!ind, ]


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: "E. Gordijn" <GORDIJN_E at schiphol.nl>
To: <r-help at stat.math.ethz.ch>
Sent: Thursday, December 07, 2006 8:48 AM
Subject: [R] Splitting a dataframe at the results of tapply


>I have got a dataframe containing measurement of aircraft noise like
> this:
>
>> Id <- c(1,4,5,2,3,6,4,1,2,5,6,3)
>> Noise <- c(88,94,97,98,92,56,103,102,87,95,92,97)
>> Height <- c(190, 150, 120, 115, 188, 104, 101, 189, 146, 111, 124,
> 126)
>>
>> df <- data.frame(Id, Noise, Height)
> Now I would like to split this in two new dataframes. The first one
> containing the rows with the maximum Noise for each Id and in the 
> second
> the other rows.
>
> I manage to find that maximum Noise levels...
>
>> m <- tapply(df$Noise, Id.factor, max)
>> m
>   1   2   3   4   5   6
> 102  98  97 103  97  92
>
> But how do I split my dataframe?
>
>
> -- 
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>
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