Re: [R] Large loops hang?

From: jim holtman <jholtman_at_gmail.com>
Date: Thu, 28 Feb 2008 20:58:30 -0500

If you really want to do a loop, then preallocate your storage. You were dynamically allocating each time through (or there abouts):

> system.time({

+ res <- numeric(100000)
+ for (i in 1:100000) {
+        x <- rnorm(2)
+        res[i] <- x[2] - x[1]
+        }
+ })

   user system elapsed
   2.75 0.02 3.10

On Thu, Feb 28, 2008 at 3:30 PM, Minimax <minimax_at_hell.org> wrote:
> Dear useRs,
>
> Suppose we have loop:
>
> res <- c()
> for (i in 1:100000) {
> x <- rnorm(2)
> res <- c(res,x[2]-x[1])
> }
>
> and this loop for 10^5 cases runs about - for example 5 minutes.
>
> When I add one zero (10^6) this loop will not end overnight but probably
> hangs. This occurs regardless of calculated statistics in such
> simulation, always above 10^5 times. Nested loops do not help.
>
> Any suggestions for collecting larger amount of Monte Carlo data ?
>
> Regards
>
> Minimax
>
> ______________________________________________
> 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.
>

-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390

What is the problem you are trying to solve?  Tell me what you want to
do, not how you want to do it.

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Received on Fri 29 Feb 2008 - 02:07:46 GMT

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