[R] Foreach help!

R. Michael Weylandt michael.weylandt at gmail.com
Thu Aug 2 01:20:25 CEST 2012


I believe that foreach() only goes along the "shorter" of the
iteration vectors.

E.g.,

foreach(.combine = c, i = 1:10, j = 1:15) %do% print(i + j)

stops when i == 10 (and j = 10 as well). To make it more explicit

foreach(.combine = c, i = 1:10, j = 11:25) %do% print(i + j)

stops when j = 20 because you run out of "i"

foreach does not seem designed for exhaustive search -- you might need
expand.grid() or some such if you want the cartesian product of ii and
jj.

Best,
Michael

On Wed, Aug 1, 2012 at 9:09 AM, Cloneberry <cloneberry at gmail.com> wrote:
> Hi,
> just during these vacation days, I'm trying to approach with multicore
> package
> and I have some troubles with foreach.
>
> ex.
> foreach(.combine=c, ii=1:200, jj=1:500) %dopar% makefunction[ii,jj]
>
> Command seem to work but if I see ii and jj value at the and of cycle, they
> are both 200
> instead than ii=200 and jj=500.
>
> Why??
> Can someone help me?
>
> Thank you in advance.
>
> Max
>
>
>
>
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