Re: [R] R perfomance question !!!

From: diver495 <ansolid_at_gmail.com>
Date: Wed, 18 Jun 2008 23:09:23 -0700 (PDT)

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
>
> ______________________________________________
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> PLEASE do read the posting guide
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>
>
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Received on Thu 19 Jun 2008 - 07:17:59 GMT

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