[R] R Parallel question

Uwe Ligges ligges at statistik.tu-dortmund.de
Sun Feb 12 19:12:51 CET 2012



On 11.02.2012 23:12, slbfelix wrote:
> Hi All,
>
> I have a question about R parallel computing by using snowfall.
>
> How can I set the seeds on parallel workers to get the same result as
> sequential mode?
>
> For example:
>
>> sfSapply(c(1,1),rnorm)
> [1]  1.823082 -2.222052
>> rnorm(2)
> [1] -0.5179967 -1.0807196
>
> How to get the identical result?

I don't think you easily can do it, since each node in a cluster has its 
own stream. Repoducing this on a different number of nodes would mean to 
jump around in the RNG stream whcih would be slow (and probably needs 
some programming work).

For a start, read ?RNG

Uwe Ligges



>
> Thanks.
> Libo Sun
>
> Graduate Student,
> Department of Statistics,
> Colorado State University
> Fort Collins, CO
>
>
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