[R] R perfomance question !!!

[diver495]

The main task is computing of consistently received data. I have a function
named "GiveNextDataPortion()" that returns the list object. The number of
function's calls is about 5 millions and thus, I encountered a problem of
perfomance.

I use this script:

x<-GiveNextDataPortion()
while(is.null(x)==FALSE)
{
    x<-GiveNextDataPortion()
}

5 millions iterations of "while" loop takes about 20 seconds on my computer,
it is very quickly, but adding some simple extra operators increases the
time of test a lot. 
For example:

x<-GiveNextDataPortion()
i=0
j=1
while(is.null(x)==FALSE)
{
   x<-GiveNextDataPortion()
   i=i+1
   j= j*i
}

It will already take more than 10 minutes. 

Have you any ideas about the optimization of this test?


Roland Rau-3 wrote:
> 
> Hi,
> 
> diver495 wrote:
>> Using Visual Basic I can complete the same script (simple loop of 5000000
>> itterations) in 0.1 sec.
>> Is it realy R not suitable for huge computing.
> 
> If you are happy with Visual Basic, then there is no need for you to use
> R.
> In case your message was not a flamebait, it is well known that loops 
> like these are often bottlenecks for R.
> 
> There are many resources how to easily avoid them. See, for example, "S 
> Programming by Venables and Ripley or John Chambers' book: Programming 
> with data.
> Even searching the mail archive for subject like "avoid loops" might be 
> helpful.
> You might also consider checking functions like apply, tapply, ...
> 
> Best,
> Roland
> 
> P.S.
> It seems there is also a good book available for scientific computing 
> with Visual Basic:
> http://www.ibiblio.org/Dave/Dr-Fun/df200002/df20000210.jpg
> 
> ______________________________________________
> 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.
> 
> 

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