Re: [R] Infinite loop

From: jim holtman <jholtman_at_gmail.com>
Date: Tue, 22 Mar 2011 17:04:25 -0400

Some systems (both hardware and software) may have "watchdog" timers; I was just using it to illustrate a point as to one way of breaking out. In the case of this loop, it probably run too fast to try and put a timer on it; counting the iterations is good enough. There are some ways of creating timers in R, but I have not used them.

On Tue, Mar 22, 2011 at 1:32 PM, Hosack, Michael <mhosack_at_state.pa.us> wrote:
> Thank you Jim, I was not aware of watchdog timers. R is my first computer language. I searched through the archives and found the function setTimeLimit and applied it with low values for cpu and elapsed time. It provides a way out of the loop which is what I needed. It's not a counter, but I could not find any info. on them in the R archives.
>
> Thanks again
>
> Mike
>
>
> -----Original Message-----
> From: jim holtman [mailto:jholtman_at_gmail.com]
> Sent: Tuesday, March 22, 2011 1:00 PM
> To: Hosack, Michael
> Cc: r-help_at_R-project.org
> Subject: Re: [R] Infinite loop
>
> The simple thing to do is to put a sanity counter in the 'repeat'
> statement and if you have been through it a certain number of times,
> then exit.  Anytime you have a loop that might run forever, you should
> have some sanity/watchdog timer on it.
>
> On Tue, Mar 22, 2011 at 11:02 AM, Hosack, Michael <mhosack_at_state.pa.us> wrote:
>> R experts,
>>
>> Hello, I am trying to sample a vector 1:40 without replacement such that no element in the new vector
>> is within 7 units of either of its immediate neighbors. This is part of a larger program I am working
>> on. The following code works well about 65 % of the time (14/40). The problem I encounter happens when
>> the last element remaining to be sampled from the vector STRATA is within 7 digits +- of the last element
>> in the vector s1, at which point an infinite loop occurs. At least that's what I think is happening.
>> Any help would be greatly appreciated.
>>
>> Thank you,
>>
>> Mike
>>
>> require(IRanges)
>> STRATA <- 1:40
>> s1 <- sample(STRATA, 1)
>> for (i in seq(from = 1, to = 39, by = 1)){
>>  repeat{
>>    tmp <- sample(STRATA, 1)
>>    if (!any(s1 == tmp) & !any(as.vector(IRanges(s1[length(s1)]-7, s1[length(s1)]+7)) %in% tmp)) break
>>    }
>>  s1 <- c(s1,tmp)
>> }
>> s1
>>
>> ______________________________________________
>> R-help_at_r-project.org mailing list
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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.
>>
>
>
>
> --
> Jim Holtman
> Data Munger Guru
>
> What is the problem that you are trying to solve?
>

-- 
Jim Holtman
Data Munger Guru

What is the problem that you are trying to solve?

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Received on Tue 22 Mar 2011 - 21:10:41 GMT

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