[R] Getting different results with set.seed()

[Jan van der Laan]

What you could also try is check if the self coded functions use the 
random generator when defining them:

starting_seed <- .Random.seed

Step 1. Self-coded functions (these functions generate random numbers as 
well)

# check if functions have modified the seed:
all.equal(starting_seed, .Random.seed)

Step 2: set.seed (123)



What has also happened to me is that some of the functions I called had 
their own random number generator independent of that of R. For example 
using one in C/C++.

Do your functions do stuff in parallel? For example using the parallel 
or snow package? In that case you also have to set the seed in the 
parallel workers.

Best,
Jan









On 19-08-2021 11:25, PIKAL Petr wrote:
> Hi
> 
> Did you try different order?
> 
> Step 2: set.seed (123)
> 
> Step 1. Self-coded functions (these functions generate random numbers as well)
> 
> Step 3: Call those functions.
> 
> Step 4: model results.
> 
> Cheers
> Petr.
> 
> And BTW, do not use HTML formating, it could cause problems in text only list.
> 
> 
> From: Shah Alam <dr.alamsolangi using gmail.com>
> Sent: Thursday, August 19, 2021 10:10 AM
> To: PIKAL Petr <petr.pikal using precheza.cz>
> Cc: r-help mailing list <r-help using r-project.org>
> Subject: Re: [R] Getting different results with set.seed()
> 
> Dear Petr,
> 
> It is more than 2000 lines of code with a lot of functions and data inputs. I
> am not sure whether it would be useful to upload it. However, you are
> absolutely right. I used
> 
> Step 1. Self-coded functions (these functions generate random numbers as well)
> 
> Step 2: set.seed (123)
> 
> Step 3: Call those functions.
> 
> Step 4: model results.
> 
> I close the R session and run the code from step 1. I get different results
> for the same set of values for parameters.
> 
> Best regards,
> Shah
> 
> 
> 
> 
> On Thu, 19 Aug 2021 at 09:56, PIKAL Petr <mailto:petr.pikal using precheza.cz>
> wrote:
> Hi
> 
> Please provide at least your code preferably with some data to reproduce
> this behaviour. I wonder if anybody could help you without such information.
> 
> My wild guess is that you used
> 
> set.seed(1234)
> 
> some code
> 
> the code used again
> 
> in which case you have to expect different results.
> 
> Cheers
> Petr
> 
>> -----Original Message-----
>> From: R-help <mailto:r-help-bounces using r-project.org> On Behalf Of Shah Alam
>> Sent: Thursday, August 19, 2021 9:46 AM
>> To: r-help mailing list <mailto:r-help using r-project.org>
>> Subject: [R] Getting different results with set.seed()
>>
>> Dear All,
>>
>> I was using set.seed to reproduce the same results for the discrete event
>> simulation model. I have 12 unknown parameters for optimization (just a
>> little background). I got a good fit of parameter combinations. However,
>> when I use those parameters combinations again in the model. I am getting
>> different results.
>>
>> Is there any problem with the set.seed. I assume the set.seed should
>> produce the same results.
>>
>> I used set.seed(1234).
>>
>> Best regards,
>> Shah
>>
>>        [[alternative HTML version deleted]]
>>
>> ______________________________________________
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>> guide.html
>> and provide commented, minimal, self-contained, reproducible code.
>>
>> ______________________________________________
>> R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
>> https://stat.ethz.ch/mailman/listinfo/r-help
>> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.