On Tue, 19 Aug 2008, Ray.Brownrigg at mcs.vuw.ac.nz wrote:
> I sent this to R-devel early last month, but have received no response, so
I guess it
> really is a bug.
Or people were busy: I was away teaching a course, for example.
> This looks like a bug to me, and is a bit hard to describe, but easy to
reproduce. ?
> Basically, if RNGkind is saved as something other than the default, and if
the first
> operation in a session is a set.seed(), the default is reverted to.
?Reproduce by:
A better description would certainly have helped! You can look at
.Random.seed to see what is happening.
I think what you are observing is that if .Random.seed has not used in the
session, any restored value is not used to set the default kind in
set.seed. I don't think that is unreasonable (in particular as you can
set the kind in set.seed() and I take the notes on ?RNG to suggest that),
but would be easy to change/document.
>
> cafe-rozo> ?R --vanilla
>
> R version 2.7.1 (2008-06-23)
> Copyright (C) 2008 The R Foundation for Statistical Computing
> ISBN 3-900051-07-0
>
> R is free software and comes with ABSOLUTELY NO WARRANTY.
> You are welcome to redistribute it under certain conditions.
> Type 'license()' or 'licence()' for distribution details.
>
> R is a collaborative project with many contributors.
> Type 'contributors()' for more information and
> 'citation()' on how to cite R or R packages in publications.
>
> Type 'demo()' for some demos, 'help()' for on-line help, or
> 'help.start()' for an HTML browser interface to help.
> Type 'q()' to quit R.
>
>> sessionInfo()
> R version 2.7.1 (2008-06-23)
> i386--netbsdelf
>
> locale:
> C
>
> attached base packages:
> [1] stats ? ? graphics ?grDevices utils ? ? datasets ?methods ? base
>> set.seed(1); runif(1)?????????# check the default
> [1] 0.2655087
>> RNGkind("Mar")
>> RNGkind()
> [1] "Marsaglia-Multicarry" "Inversion"
>> set.seed(1); runif(1)?????????# now check again
> [1] 0.006153224
>> set.seed(1)???????????????????# save seed and RNGkind
>> q("yes")
> cafe-rozo> ?R
>
> R version 2.7.1 (2008-06-23)
> : etc
> [Previously saved workspace restored]
>
>> runif(1)??????????????# with a saved seed, Marsaglia-Multicarry is used
> [1] 0.006153224
>> set.seed(1); runif(1)
> [1] 0.006153224
>> q()
> Save workspace image? [y/n/c]: n
> cafe-rozo>
>
> R version 2.7.1 (2008-06-23)
> : etc
> [Previously saved workspace restored]
>
>> set.seed(1); runif(1)?????????# saved RNGkind is ignored ...
> [1] 0.2655087
>> RNGkind()?????????????# and overridden ...
> [1] "Mersenne-Twister" "Inversion"
>> q("no")
> cafe-rozo> ?R
>
> R version 2.7.1 (2008-06-23)
> : etc
> [Previously saved workspace restored]
>
>> RNGkind()?????????????# and wrongly reported!
> [1] "Mersenne-Twister" "Inversion"
>> runif(1)??????????????????????# Note this is actually using
Marsaglia-Multicarry
> [1] 0.006153224
>>
>
> Ray Brownrigg
> Mathematics, Statistics and Computer Science
> Victoria University of Wellington
> Wellington, NZ
>
> ______________________________________________
> R-devel at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel
>
--
Brian D. Ripley, ripley at stats.ox.ac.uk
Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/
University of Oxford, Tel: +44 1865 272861 (self)
1 South Parks Road, +44 1865 272866 (PA)
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