[R] monitor variable change

[Rainer M Krug]

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On 02/16/2011 03:04 PM, Jan van der Laan wrote:
> 
> One possible solution is to use something like:
> 
> a <- 0
> for (i in 1:1E6) {
>     old.a <- a
> 
>     # do something e.g.
>     a <- runif(1) < 1E-6
> 
>     if (a != old.a) browser()
You can replace the previous line by:

browser(expr=(a!=old.a)

see ?browser for details.

> }
> 
> 
> Another solution is to write your output to file (using sink for
> example) and to watch this file using a tool like tail.
> 
> Jan
> 
> 
> 
> 
> 
> 
> Quoting Alaios <alaios at yahoo.com>:
> 
>> I think we are both talking for watchpoints-breakpoints
>>
>> --- On Wed, 2/16/11, Rainer M Krug <r.m.krug at gmail.com> wrote:
>>
>>> From: Rainer M Krug <r.m.krug at gmail.com>
>>> Subject: Re: [R] monitor variable change
>>> To: "Alaios" <alaios at yahoo.com>
>>> Cc: R-help at r-project.org
>>> Date: Wednesday, February 16, 2011, 9:54 AM
> On 02/16/2011 10:38 AM, Alaios wrote:
>> Dear all I would like to ask you if there is a way in
> R to monitor in R when a value changes.
> 
>> Right now I use the sprintf('my variables is %d \n, j)
> to print the value of the variable.
> 
>> Is it possible when a 'big' for loop executes to open
> in a new window to dynamically check only the variable I
> want to.
> 
> I don't think that this functionality is implemented.
> 
> But I guess you can implement it - would it be possible to
> re-define th
> "<-" to check if a certain variable is to be changed,
> and then print it?
> 
> Might be tricky and would slow everything considerably
> down.
> 
> Just a thought,
> 
> Rainer
> 
> 
>> If I put all the sprintf statements inside my loop
> then I get flooded with so many messages that makes it
> useless. 
> 
>> Best Regards
>> Alex
> 
>> ______________________________________________
>> 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.
> 
> 
>>>
>>
>>
>>
>>
>> ______________________________________________
>> 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.
>>

- -- 
Rainer M. Krug, PhD (Conservation Ecology, SUN), MSc (Conservation
Biology, UCT), Dipl. Phys. (Germany)

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