[R] Creating a loop with an indefinite end term

[David Winsemius]

On Apr 10, 2012, at 11:53 AM, Steve Lavrenz wrote:

> Albyn,
>
> Thanks for your help. This however, still assumes that I have to  
> define an
> array of length 10. Is there a way that I can construct this so that  
> my
> array is exactly as long as the number of spots I need to reach my  
> threshold
> value?

 > seq(0,100, by=5)
  [1]   0   5  10  15  20  25  30  35  40  45  50  55  60  65  70  75   
80  85  90  95 100

>
> Thanks,
>
> -Steve
>
> -----Original Message-----
> From: Albyn Jones [mailto:jones at reed.edu]
> Sent: Tuesday, April 10, 2012 11:46 AM
> To: Steve Lavrenz
> Cc: r-help at r-project.org
> Subject: Re: [R] Creating a loop with an indefinite end term
>
> 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]]
>>
>> ______________________________________________
>> R-help at r-project.org 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.
>>
>
> --
> Albyn Jones
> Reed College
> jones at reed.edu
>
> ______________________________________________
> R-help at r-project.org 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.

David Winsemius, MD
West Hartford, CT