[R-pkg-devel] Change in normal random numbers between R 3.5.3 and R 3.6.0

[Martin Maechler]

>>>>> Ulrike Grömping 
>>>>>     on Fri, 10 May 2019 06:39:39 +0200 writes:

    > Mark,
    > I used

    > if (getRversion()>="3.6.0") RNGkind(sample.kind="Rounding")

    > And that works. Actually, using rnorm afterwards also
    > yields the same random numbers.

Yes, "of course",  'sample.kind' was only introduced into 3.6.0.
We had always recommended

   RNGversion("3.5.0")

possibly wrapped in  suppressWarnings().
That *does* work in old and new versions of R.

Note that in R >= 3.6.0 , e.g., inside your if(.) { ** }
you could also use  set.seed(<n>, sample.kind="Rounding")

Martin


    > My question arose from the fact that I confused myself about the noLD output I was supposed to reproduce. Therefore, my problem should be entirely explained by Duncan Murdoch's initial explanation: the sample() change does not only lead to different results in discrete sampling but also to different results from random number calls for other functions (like rnorm)

*IFF* callled after sample() [etc].
So yes, do call   RNGversion("3.5.0")
before set.seed() before the first call to sample() / sample.int()
or functions using those [or 'rwilcox()', see its help in R >= 3.6.0!].

Martin


    > Best, Ulrike

    > Am 10.05.2019 um 04:58 schrieb R. Mark Sharp:
    >> I was dealing with a similar issue but in the context of getting the same unit test code to work on multiple versions of R in a Travis-CI build. It seems RNGkind(sample.kind="Rounding”) does not work prior to version 3.6 so I resorted to using version dependent construction of the argument list to set.seed() in do.call().
    >> 
    >> I better solution will be greatly appreciated.
    >> 
    >> #' Work around for unit tests using sample()
    >> #'
    >> #' @param seed argument to \code{set.seed}
    >> set_seed <- function(seed = 1) {
    >> version <- as.integer(R.Version()$major) + (as.numeric(R.Version()$minor) / 10.0)
    >> if (version >= 3.6) {
    >> args <- list(seed, sample.kind = "Rounding")
    >> } else {
    >> args <- list(seed)
    >> }
    >> suppressWarnings(do.call(set.seed, args))
    >> }
    >> 
    >> Mark
    >> 
    >> R. Mark Sharp, Ph.D.
    >> Data Scientist and Biomedical Statistical Consultant
    >> 7526 Meadow Green St.
    >> San Antonio, TX 78251
    >> mobile: 210-218-2868
    >> rmsharp using me.com
    >> 
    >> 
    >> 
    >> 
    >> 
    >> 
    >> 
    >> 
    >> 
    >> 
    >> 
    >>> On May 9, 2019, at 12:45 PM, Duncan Murdoch <murdoch.duncan using gmail.com> wrote:
    >>> 
    >>> On 09/05/2019 12:43 p.m., Ulrike Grömping wrote:
    >>>> Hmmmh, but does that also apply if the sample.kind has been set to the
    >>>> old version? I.e., would
    >>>> if (getRversion()>="3.6.0") RNGkind(sample.kind="Rounding")
    >>>> val <- 10
    >>>> set.seed(val)
    >>>> discard <- sample(1000, 100)
    >>>> rnorm(36)
    >>>> produce the same normal random numbers in 3.5.3 and 3.6.0? I would have
    >>>> expected it to, but it seems to produce the same normal random numbers
    >>>> as R version 3.6.0 in the previous version of the test code without the
    >>>> RNGkind call.
    >>> I'm not seeing that, but I'm not using the exact versions you tested. If I run your code in  "R version 3.5.2 (2018-12-20)" and "R Under development (unstable) (2019-05-02 r76454)" I get this output from both:
    >>> 
    >>>> if (getRversion()>="3.6.0") RNGkind(sample.kind="Rounding")
    >>>> val <- 10
    >>>> set.seed(val)
    >>>> discard <- sample(1000, 100)
    >>>> rnorm(36)
    >>> [1] -0.4006375 -0.3345566  1.3679540  2.1377671  0.5058193  0.7863424 -0.9022119  0.5328970 -0.6458943  0.2909875 -1.2375945
    >>> [12] -0.4561763 -0.8303227  0.3401156  1.0663764  1.2161258  0.7356907 -0.4812086  0.5627448 -1.2463197  0.3809222 -1.4304273
    >>> [23] -1.0484455 -0.2185036 -1.4899362  1.1727063 -1.4798270 -0.4303878 -1.0516386  1.5225863  0.5928281 -0.2226615  0.7128943
    >>> [34]  0.7166008  0.4402419  0.1588306
    >>> 
    >>> Okay, I just installed 3.6.0, and I get the same values there.  I don't see a Mac binary for 3.5.3, so I can't test that one.
    >>> 
    >>> Duncan Murdoch
    >>> 
    >>> ______________________________________________
    >>> R-package-devel using r-project.org mailing list
    >>> https://stat.ethz.ch/mailman/listinfo/r-package-devel


    > -- 
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    > ## FB II
    > ## Beuth University of Applied Sciences Berlin
    > ##############################################
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