---------- Forwarded message ---------- From: Antonio Paredes <antonioparede...@gmail.com> Date: Tue, Oct 6, 2009 at 9:41 AM Subject: Re: [R] Long for Loop- calling C from R - Parallel Computing To: Karl Ove Hufthammer <k...@huftis.org>
Hello again, I'm hoping to get a response from some of the R gurus in this list. Is my assumption that R is not designed or build to deal with high levels (a lots of simulated data) simulation correct. For example, how to minimize system time; do one have to call a lower level language like C or Fortran; or just, like many of you have done, do a lots of programing in R and eventually the tricks will be learned. Thanks On Mon, Oct 5, 2009 at 8:35 AM, Antonio Paredes <antonioparede...@gmail.com>wrote: > In my case it does, because I need to preserved a "high level" of > independence (lack of correlation) among the different groups of 60. Also, > when I say final result I mean computation of standard errors and that > source of stuff; sorry about the lack clarity in my statement. > > > On Mon, Oct 5, 2009 at 9:48 AM, Karl Ove Hufthammer <k...@huftis.org>wrote: > >> In article <6f6f0fd60910050629p28c99209jcd7836353fd2d754 >> @mail.gmail.com>, antonioparede...@gmail.com says... >> > I'm running the following for loop to generate random variables in >> chunks of >> > 60 at a time (l), here h is of order in millions (could be 5 to 6 >> millions), >> > note that generating all the variables at once could have an impact on >> the >> > final results >> >> No, it will not. See this example code for an illustration: >> >> set.seed(1) >> rnorm(3) >> rnorm(3) >> set.seed(1) >> rnorm(6) >> >> So if you generate the six numbers three at a time or all at once gives >> exactly the same result. >> >> So my suggestion is to generate all the numbers at once. That takes next >> to no time. Or, if it takes too much memory, generate for example a >> million at once, and repeat a few times. >> >> -- >> Karl Ove Hufthammer >> >> ______________________________________________ >> R-help@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. >> > > > > -- > -Tony > -- -Tony -- -Tony [[alternative HTML version deleted]] ______________________________________________ R-help@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.
