R help - Dec 2006 - 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?
 
 
-- 
    Ed Gordijn
    Adviseur geluidscapaciteit

    Amsterdam Airport Schiphol
    Business Area Aviation (A/CAP/EC)
    Postbus 7501,  1118 ZG  Schiphol 
    Bezoekadres: Evert v/d Beekstraat 202, 1118 CP  Schiphol

    tel       020 601 32 22
    fax      020 601 21 34
    e-mail  gordijn_e@schiphol.nl 

    meer informatie is te vinden op www.schiphol.nl 
--


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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?
>
>
> -- 
>    Ed Gordijn
>    Adviseur geluidscapaciteit
>
>    Amsterdam Airport Schiphol
>    Business Area Aviation (A/CAP/EC)
>    Postbus 7501,  1118 ZG  Schiphol
>    Bezoekadres: Evert v/d Beekstraat 202, 1118 CP  Schiphol
>
>    tel       020 601 32 22
>    fax      020 601 21 34
>    e-mail  gordijn_e at schiphol.nl
>
>    meer informatie is te vinden op www.schiphol.nl
> --
>
>
> -------------------------------------------------------------------
> This e-mail may contain confidential and privileged 
> material...{{dropped}}
>
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide 
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
> 

Disclaimer: http://www.kuleuven.be/cwis/email_disclaimer.htm

Hi Dimitris,

This works fine.

Thanks!, Ed
-- 

-- 
    Ed Gordijn
    Adviseur geluidscapaciteit

    Amsterdam Airport Schiphol
    Business Area Aviation (A/CAP/EC)
    Postbus 7501,  1118 ZG  Schiphol 
    Bezoekadres: Evert v/d Beekstraat 202, 1118 CP  Schiphol

    tel       020 601 32 22
    fax      020 601 21 34
    e-mail  gordijn_e at schiphol.nl 

    meer informatie is te vinden op www.schiphol.nl 
--


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