Re: [jgap-users] Problem with CrossoverOperator

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Zahir,

thanx a lot for your clarification and correction!
I think WeightedRouletteSelector needs some adaption. Or even better: JGAP
should be restructured to keep the cloning issue and other things like this
away from the selectors.

Best

Klaus
www.klaus-meffert.com

> -----Original Message-----
> From: Zahir Bishnani [mailto:zbi...@al...] 
> Sent: Monday, January 21, 2008 6:55 PM
> To: 'Klaus Meffert'; jga...@li...
> Subject: RE: [jgap-users] Problem with CrossoverOperator
> 
> Hi Klaus,
> 
> Thanks for the quick fix. I just gave it a try but it didn't 
> work! I couldn't see where it actually calls isXoverNewAge()...
> 
> I changed line 76 from:
> 
> 	if (chrom1.getAge() < 1 && chrom2.getAge() < 1) {
> 
> to:
> 
> 	if (!isXoverNewAge() && chrom1.getAge() < 1 && 
> chrom2.getAge() < 1) {
> 
> and now it works...
> 
> 
> Also, WeightedRouletteSelector uses a cloned chromosome only 
> if it has been selected already for the new population. If 
> not, it just uses the old instance. So Crossover did work 
> occasionally but not correctly.
> 
> Cheers,
> 
> Zahir.
> 
> 
> -----Original Message-----
> From: Klaus Meffert [mailto:jg...@kl...]
> Sent: 20 January 2008 09:49
> To: 'Zahir Bishnani'; jga...@li...
> Subject: RE: [jgap-users] Problem with CrossoverOperator
> 
> Zahir,
> 
> good information detail! I could not see why 
> WeightedRouletteSelector shouldn't use cloning, I think it 
> does (maybe in an older version it does not).
> However, I enhanced class Crossover and checked it in to CVS. 
> Now you can either use a new constructor with parameter 
> a_xoverNewAge. Or you can use
> setXoverNewAge(true) after constructing your configuration. 
> In case you use a DefaultConfiguration, please proceed as 
> shown, e.g., in class DynamicMutationExample, where default 
> genetic operators are replaced or reconfigured.
> 
> Best
> 
> Klaus
> www.klaus-meffert.com
>  
> 
> > -----Original Message-----
> > From: jga...@li...
> > [mailto:jga...@li...] On Behalf 
> Of Zahir 
> > Bishnani
> > Sent: Friday, January 18, 2008 8:02 PM
> > To: jga...@li...
> > Subject: [jgap-users] Problem with CrossoverOperator
> > 
> > Hi,
> > 
> > I'm having a problem with CrossoverOperator. Using the 
> > DefaultConfiguration I can't get it to function.
> > 
> > After applying the BestChromosomesSelector, all current chromosomes 
> > copied across to the next generation have their age reset to 0. It 
> > appears they are being cloned to new ones.
> > 
> > CrossoverOperator.select() then ignores all these newly created 
> > chromosomes under the assumption that it is not beneficial to 
> > crossover new ones.
> > 
> > This cloning doesn't occur when using a WeightedRouletteSelector so 
> > crossover does work here.
> > 
> > I also noticed a problem with setPreservFittestIndividual 
> as mentioned 
> > in a previous mail.
> > 
> > Cheers,
> > 
> > Zahir.
> > 
> > ------------------------------
> > 
> > Message: 8
> > Date: Thu, 10 Jan 2008 14:18:28 -0500
> > From: "Oscar Miguel Alonso M" <oma...@gm...>
> > Subject: [jgap-users] Problem with setPreservFittestIndividual
> > To: jga...@li...
> > Message-ID:
> > 	<35c...@ma...>
> > Content-Type: text/plain; charset=ISO-8859-1
> > 
> > Hello!!
> > 
> > I had problems with the option setPreservFittestIndividual() of the 
> > Configuration class. Although I set it to true, sometimes 
> the fitness 
> > of the fittest individual decreases from one generation to the next 
> > one. I browsed the source code and I think that there is a 
> bug in the 
> > class GABreeder, in line 45.
> > 
> > It is
> > 
> > fittest = pop.determineFittestChromosome(0, originalPopSize - 1);
> > 
> > and I think it should be
> > 
> > fittest = pop.determineFittestChromosome(0, pop.size() - 1);
> > 
> > because the fittest individual is added by the breeder at 
> the end of 
> > the population, and the current population size may be greater than 
> > the one defined in the configuration.
> > 
> > Manually adding the fittest individual at the beginning of the 
> > population solved my problem. Please tell me if I am right 
> or if there 
> > is a better way of ensuring that the best individual is 
> preserved for 
> > the next generation.
> > 
> > Best regards,
> > Oscar M
> > 
> > 
> > 
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