[R] Creating a loop with an indefinite end term

[Albyn Jones]

Here are a couple of constructions that work.  

albyn
===========================================

num <- rep(0,10)
for (i in 2:10)   { 
      num[i] <- num[i-1] + 5 
      if(num[i] > 20) break
} 
> num
 [1]  0  5 10 15 20 25  0  0  0  0

or

num <- rep(0,10)
done <- FALSE
i <- 2
while(!done){
     num[i] <- num[i-1] + 5
     if(num[i] > 20) done <- TRUE
     i <- i + 1
}
> num
 [1]  0  5 10 15 20 25  0  0  0  0


On Tue, Apr 10, 2012 at 10:48:34AM -0400, Steve Lavrenz wrote:
> Everyone, 
> 
> I'm very new to R, especially when it comes to loops and functions, so
> please bear with me if this is an elementary question. I cannot seem to
> figure out how to construct a loop which runs a function until a certain
> value is computed. For example, say I have the following: 
> 
> num = numeric (10) 
> num [1] = 0 
> for (i in 2:10)   { 
>       num [i] = num [i-1] + 5 
> } 
> 
> This adds 5 to the preceding spot of a vector of length 10 to get the value
> in the current spot. However, say I don't just want to run this for 10
> spots; rather I want to run it until a certain value (say, 100) is computed.
> How I construct my loop to do this? 
> 
> Thanks!
> 
> 
> 	[[alternative HTML version deleted]]
> 
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> 

-- 
Albyn Jones
Reed College
jones at reed.edu