You might consider the rlecuyer package, which provides parallel streams and avoids the potential worst case scenario from arbitrary seed setting.
On 5/25/05, Dr L. Y Hin <[EMAIL PROTECTED]> wrote: > Dear all, > Apologies for this pedantic question that only arise when there is hardware > limitation. > Setting: R 2.1.0 for windows xp sp2. > Scenario: > To generate 1000 samples using rnorm for a simulation activity. > Background: > The simulation activity requires so much memory resources that generating > 200 samples > clogs up the PF usage as indicated in the Windows Task Manager. > Therefore, short of implementing the simulation on a computer with more > resources, > the alternative is to generate the 1000 samples in 5 separate runs, > each generating 200 samples, closing the R window and re-opening between > runs. > Question to be addressed: > To maintain consistency and ensure reproducibility of the simulation > results, the 1000 samples > generated in one single run should be indentical to the 5x200 samples > generated on 5 separate > runs. > While such consistency can be ensured using set.seed() in the case of one > single run, in the case > where 5 separate runs are performed, can we do the following to ensure > identical samples being > generated? > 1. In the first run, specify the seed by, say, set.seed(1) > > 2. At the end of the first run, store the .Random.seed by the following > manner: > saved.seed.1<-.Random.seed > > 3. At the beginning of the second run, assign the saved.seed.1 to > .Random.seed as follows: > .Random.seed<-saved.seed.1 > > 4. At the end of the first run, store the new .Random.seed by the following > manner: > saved.seed.2<-.Random.seed > > 5. At the beginning of the second run, assign the saved.seed.2 to > .Random.seed as follows: > .Random.seed<-saved.seed.2 > > This is repeated until 5 runs are completed. > > Will the paths of random number generation be identical in these two > approaches? If not, is there > a way to ensure this? > > Apologies again for this long-winded inquiry. > > Thank you. > Best > Lin > > ______________________________________________ > R-help@stat.math.ethz.ch mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html > -- best, -tony "Commit early,commit often, and commit in a repository from which we can easily roll-back your mistakes" (AJR, 4Jan05). A.J. Rossini [EMAIL PROTECTED] ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
