[R] Large loops hang?

[jim holtman]

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
>
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> 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.