R help - Mar 2007 - Trimming a Data Set

Hi,

I am trying to restrict a data set so as not to included outliers. 
Specifically, I would like to specify a percentage where a fraction of
observations are eliminated from the data set, much in the same way that the
trimmed mean function works - but leaving the restricted data set intact.

I have been using a function which will restrict the data set
using:
> trim=function(x,p){
> o=order(x)
> xo=x[o]
> n=length(xo)
> tl=round(n*p)
> print(xo[(tl+1):(n-tl)])}
However I was wondering if anyone knew a more elegant and simple method to get
the same result.

Thanks in advance.


 
---------------------------------
Don't pick lemons.

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If it is precise enough for you, you can use

trim <- function(x,prop=.05) {
trimx <- x[x < quantile(x,prob=(1-prop))]
return(trimx)
}

Petr

Jonathan Morse napsal(a):
> Hi,
> 
> I am trying to restrict a data set so as not to included outliers. 
Specifically, I would like to specify a percentage where a fraction of
observations are eliminated from the data set, much in the same way that the
trimmed mean function works - but leaving the restricted data set intact.
> 
> I have been using a function which will restrict the data set using:
>> trim=function(x,p){
>> o=order(x)
>> xo=x[o]
>> n=length(xo)
>> tl=round(n*p)
>> print(xo[(tl+1):(n-tl)])}
> 
> However I was wondering if anyone knew a more elegant and simple method to
get the same result.
> 
> Thanks in advance.
> 
> 
>  
> ---------------------------------
> Don't pick lemons.
> 
> 	[[alternative HTML version deleted]]
> 
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> 
-- 
Petr Klasterecky
Dept. of Probability and Statistics
Charles University in Prague
Czech Republic