From Ray.Brownrigg at mcs.vuw.ac.nz  Tue Aug 19 07:15:09 2008
From: Ray.Brownrigg at mcs.vuw.ac.nz (Ray.Brownrigg at mcs.vuw.ac.nz)
Date: Tue, 19 Aug 2008 07:15:09 +0200 (CEST)
Subject: [Rd] RNGkind() state (PR#12567)
Message-ID: <20080819051509.871CA282C768@mail.pubhealth.ku.dk>

I sent this to R-devel early last month, but have received no response, so I guess it 
really is a bug.

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:

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



[Rd] RNGkind() state (PR#12567)
Ray.Brownrigg at mcs.vuw.ac.nz