[R] package:AlgDesign and .Random.seed [Broadcast]

Liaw, Andy andy_liaw at merck.com
Wed Mar 21 15:21:01 CET 2007


From: Michael Kubovy
> 
> On Mar 21, 2007, at 4:16 AM, Uwe Ligges wrote:
> 
> > Michael Kubovy wrote:
> >> Dear r-helpers,
> >> Could you please help me solve the following problem: When I run
> >> require(AlgDesign)
> >> trt <- LETTERS[1:5]
> >> blk <- 10
> >> trtblk <- 3
> >> BIB <- optBlock(~., withinData = trt, blocksizes = 
> rep(trtblk, blk)) 
> >> In response to the last command, R complains:
> >> Error in optBlock(~., withinData = trt, blocksizes = rep(trtblk,
> >> blk)) :
> >> 	object ".Random.seed" not found
> >> The documentation of optBlock() in AlgDesign doesn't say that I   
> >> needed to set .Random.seed. I thought it was initiated 
> automatically  
> >> at the beginning of a session. What am I missing?
> >
> >
> > The first line in that function is
> >     seed <- .Random.seed
> > but .Random.seed is generated at the first use of R's RNG, hence  
> > maybe later. This means the function contains a bug which you  
> > should report to the package maintainer, please.
> >
> > Best,
> > Uwe Ligges
> 
> Bob Wheeler's response:
> 
> > From: Bob Wheeler <rwheeler at echip.com>
> > Date: March 21, 2007 9:19:29 AM EDT
> > To: Michael Kubovy <kubovy at virginia.edu>
> > Subject: Re:
> >
> > Each workspace in R requires you to set a random seed to 
> start. You  
> > have not done this. It is an R artifact, and has nothing to 
> do with  
> > AlgDesign.

I do not agree with that assessment (well, it's just my $0.02 anyway).
I don't need a random seed unless I'm doing computations that requires
pseudo-random numbers.  There are plenty of times I use R without
needing random seed.

None of the builtin RNGs in R requires explcit seed setting, nor does
any of the ones in the contributed packages that I know of.  Thus I
would claim that's a flaw in AlgDesign.

Andy

> > -- 
> > Bob Wheeler --- http://www.bobwheeler.com/
> >    ECHIP, Inc. --- Randomness comes in bunches.
> 
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> 
> 


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