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June 2015

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ECJ Evolutionary Computation Toolkit <[log in to unmask]>
Date:
Wed, 3 Jun 2015 17:04:44 -0400
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ECJ Evolutionary Computation Toolkit <[log in to unmask]>
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Eric 'Siggy' Scott <[log in to unmask]>
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All good questions.  That's why I was looking at the code -- to see how
exactly "the standard deviation is scaled to reflect each gene's range."

I can specify mutation-stdev's manually for each gene in my application,
not a problem.  I suggest that the sentence about scaling be removed from
the JavaDoc, as it seems to be erroneous.

Thanks!
Siggy

On Wed, Jun 3, 2015 at 3:38 PM, Sean Luke <[log in to unmask]> wrote:

> No, wait, it's *not* a bug.  ECJ's stdev is not scaled to fit in bounds.
> You'd have to say:
>
> >> pop.subpop.0.species.mutation-stdev.0 =   0.0001
>
> [or whatever]
>
> I understand your intuition here, but stdev is a fixed quantity.  Imagine
> if someone had the stdev set and then they needed to change the min/max
> gene, and found that the stdev magically changed as well.  And if it were a
> relative quantity, what min/max width range would it be relative *to*?
>
> Maybe I might be able to add some parameter like mutation-rstdev which
> sets the stdev on a per-gene basis based on the min and max genes.  But
> you'd need to give me exactly what it should be relative to and how you
> think it should be scaled.
>
> Sean
>
> On Jun 3, 2015, at 8:16 AM, Sean Luke <[log in to unmask]> wrote:
>
> > Then that must be a bug.  I can look into it, but if you want to beat me
> to it, you might check out FloatVectorSpecies.
> >
> > Sean
> >
> > On Jun 3, 2015, at 4:20 AM, Eric Scott <[log in to unmask]> wrote:
> >
> >> Dear Wizards,
> >>
> >> The JavaDoc for FloatVectorSpecies claims that when using Guassian
> mutation, "if the gene-by-gene range is used, than the standard deviation
> is scaled to reflect each gene's range."
> >>
> >> As far as I can tell, however, this doesn't actually happen.  Stepping
> through the debugger with the following mutation parameters, I can watch
> DoubleVectorIndividual.gaussianMutation() as it samples from a std of 0.1
> when mutation gene 0.  I would have expected it to scale the std to be
> 0.0001 or such.
> >>
> >> pop.subpop.0.species.min-gene =         -1.0
> >> pop.subpop.0.species.max-gene =         1.0
> >> pop.subpop.0.species.min-gene.0 =         -.001
> >> pop.subpop.0.species.max-gene.0 =         .001
> >> pop.subpop.0.species.mutation-type =    gauss
> >> pop.subpop.0.species.mutation-stdev =   0.1
> >> pop.subpop.0.species.mutation-bounded = true
> >> pop.subpop.0.species.mutation-prob =    0.03
> >>
> >> Is this an error in the documentation? Or am I missing something?
> >>
> >> Thanks,
> >> Siggy
> >>
> >> --
> >>
> >> Ph.D student in Computer Science
> >> George Mason University
> >> http://mason.gmu.edu/~escott8/
>



-- 

Ph.D student in Computer Science
George Mason University
http://mason.gmu.edu/~escott8/


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