
Hi, 
You should use the sapply/lapply for such operations.

> r<-round(runif(100000,1,10))
> head(r)
[1] 3 7 6 3 2 8
> filt<-function(x,thres) ifelse(x<thres,x,thres)
> system.time(r2<-sapply(r,filt,thres=5))
   user  system elapsed 
   3.36    0.00    3.66 
> head(r2)
[1] 3 5 5 3 2 5


To return a list, replace "sapply" with "lapply"

Christos



> Date: Mon, 21 Jun 2010 11:34:01 +0100
> From: james@ipec.co.uk
> To: r-help@r-project.org
> Subject: [R]  Replacing elements of a list over a certain threshold
> 
> Dear List,
> 
> I have a list of length ~1000 filled with numerics. I need to replace 
> the elements of this list that are above a certain numerical threshold 
> with the value of the threshold.
> 
> e.g
> example=list(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1)
> threshold=5
> <magic code goes here>
> example=(1, 2, 3, 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 4, 3, 2, 1).
> 
> I have written a crude script that achieves this but it's very slow. Is 
> there a way to do this using some R function?
> 
> Crude script: http://pastebin.com/3KSfi8nD
> 
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> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
 		 	   		  
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