[R] R Parallel question

[Uwe Ligges]

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
>
>
> --
> View this message in context: http://r.789695.n4.nabble.com/R-Parallel-question-tp4380098p4380098.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> 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.