[R] package:AlgDesign and .Random.seed

[Uwe Ligges]

So let me read the help page of ?RNG for all of us:

"Initially, there is no seed; a new one is created from the current time 
when one is required. Hence, different sessions will give different 
simulation results, by default."

Hence this is definitely a bug in AlgDesign.

Further on also remarkable for Bob Wheeler's decision to save .Random.seed:

".Random.seed saves the seed set for the uniform random-number 
generator, at least for the system generators. It does not necessarily 
save the state of other generators, and in particular does not save the 
state of the Box–Muller normal generator. If you want to reproduce work 
later, call set.seed rather than set .Random.seed."


Uwe Ligges




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