package load altering RNG state

Henric Winell <nilsson.henric at gmail.com>
     on Tue, 7 Feb 2017 13:37:42 +0100 writes:

     > Hi, On 2017-02-07 13:12, Benjamin Tyner wrote:

     >> Hello
     >>
     >> When loading a package, I'm wondering if it's frowned
     >> upon for the package to alter the state of the random
     >> number generator? I guess not, since the parallel package
     >> does it?

     > Surprisingly it is not frowned upon, but it *is* a
     > nuisance.  I brought it up a couple of years ago

     > http://r.789695.n4.nabble.com/parallel-package-changes-Random-seed-td4686321.html

     > along with a patch, but was told off...

     >>

     >> > set.seed(6860) > old.seed <- .GlobalEnv$.Random.seed >

     >> library(parallel) > new.seed <- .GlobalEnv$.Random.seed >
     >> identical(old.seed, new.seed) [1] FALSE
     >>
     >> I ask because, I found myself writing a custom wrapper
     >> around library() to restore the original RNG state, in
     >> order to increase reproducibility.  But now wondering if
     >> others would welcome such a feature to be added to base
     >> R? Either something very general like
     >>
     >> preserveRNGstate(library(parallel))
     >>
     >> or perhaps an specific enhancement to library itself?

     > I would very much welcome a change, but in the light of
     > things it doesn't seem likely.

     > Henric Winell

Sometimes things change ... and not always for the worse.  I've
found a version of your original patch idea which is very
efficient nice (in my eyes) and still leaves
	system.time(loadNamespace("parallel"))
to round to 0, i.e. needing less than 1 ms.

    --> in R-devel svn rev 72136

Martin