[R] Same initial seed

[diegol]

Great. Your suggestion is most welcome, everything is clear now.

Thank you for your time, Duncan!


Regards,
Diego



Duncan Murdoch-2 wrote:
> 
> diegol wrote:
>> Hello,
>>
>> I have tried a few searches without luck before posting, since this one
>> seems a pretty basic question. 
>> I am using R 2.7.0 on WinXP, as I have long started using this version
>> for
>> my thesis work and am reluctant to update fearing consistency/backward
>> compatibility issues could happen.
>>
>> I noticed that whenever I start an R session (launch the console
>> application) and run a script involving random number generation, eg:
>>
>>   
>>> rnorm(10)
>>>     
>>
>> I get the same result. In fact, each time I start a new R session and
>> enter
>>
>>   
>>> .Random.seed
>>>     
>>
>> I get the same exact vector. From ?.Random.seed:
>>
>> "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." (as stated in R 2.7.0's documentation)
>>
>> When I try RSiteSearch(".Random.seed") I get this updated result:
>>
>> "Initially, there is no seed; a new one is created from the current time
>> when one is required. Hence, different sessions started at (sufficiently)
>> different times will give different simulation results, by default.
>> However,
>> the seed might be restored from a previous session if a previously saved
>> workspace is restored."
>>
>> My PC clock is working fine. I think the problem is not related to
>> allotting
>> "sufficient" time between sessions either, which leads me to think this
>> has
>> to do with a previously saved workspace, which in the case I mention is
>> indeed restored.
>>
>> I would like to generate different random numbers in each session. The
>> two
>> choices I seem to have are: 
>> i) Not restore the workspace so a new seed is created from the current
>> time
>> (I have to look into how to go about this); 
>>   
> 
> That's the best choice.  Why do you want all the leftovers from the 
> previous session?  It's better to start with a clean slate.
> 
>> ii) Leave the workspace alone and manually set a new seed via set.seed()
>>   
> 
> That's a good idea to make your work reproducible.  This is not 
> exclusive of i); do both.
>> Am I leaving any options out or getting something wrong?
>>   
> 
> A third choice is to remove .Random.seed, and then the timer will be 
> used to regenerate it.   But i) *and* ii) are better ideas.
> 
> Duncan Murdoch
>> Thank you.
>>
>> -----
>> ~~~~~~~~~~~~~~~~~~~~~~~~~~
>> Diego Mazzeo
>> Actuarial Science Student
>> Facultad de Ciencias Económicas
>> Universidad de Buenos Aires
>> Buenos Aires, Argentina
>>
> 
> ______________________________________________
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> PLEASE do read the posting guide
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> 
> 


-----
~~~~~~~~~~~~~~~~~~~~~~~~~~
Diego Mazzeo
Actuarial Science Student
Facultad de Ciencias Económicas
Universidad de Buenos Aires
Buenos Aires, Argentina
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