[galib] Getting several genomes of only 0's...
anselmop@sc.usp.br
anselmop at sc.usp.br
Thu Jan 3 14:13:05 EST 2008
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> 1. Re: Getting several genomes of only 0's... (David Love)
> 2. Compiling a Windows Form Application with Visual Studio
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> ----------------------------------------------------------------------
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> Message: 1
> Date: Wed, 2 Jan 2008 16:33:11 -0700
> From: David Love <wvpryde at hotmail.com>
> Subject: Re: [galib] Getting several genomes of only 0's...
> To: <galib at mit.edu>
> Message-ID: <BAY101-W205C5BDC242BCFC4A685DCB4520 at phx.gbl>
> Content-Type: text/plain; charset="Windows-1252"
>
>
>
>
> ----------------------------------------
>> Date: Sun, 23 Dec 2007 01:32:54 -0500
>> From: p at dirac.org
>> To: galib at mit.edu
>> Subject: Re: [galib] Getting several genomes of only 0's...
>>
>> On Wed 19 Dec 07, 4:57 PM, anselmop at sc.usp.br <anselmop at sc.usp.br> said:
>> > > Message: 1
>> > > Date: Tue, 18 Dec 2007 15:14:11 -0700
>> > > From: David Love <wvpryde at hotmail.com>
>> > > Subject: [galib] Getting several genomes of only 0's after completion
>> > > of first generation, before mutation and crosso
>> > > To: <galib at mit.edu>
>> > > Message-ID: <BAY101-W1050FE12A5C28FF3DD0D83B4630 at phx.gbl>
>> > > Content-Type: text/plain; charset="iso-8859-1"
>> > >
>> > >
>> > > Hi everyone,
>> > >
>> > > I'm doing a GASimpleGA using the GA1DArrayGenome data type. I've
>> > > noticed that after the GA has finished evaluating the first
>> > > generation I receive several genomes for evaluation where every gene
>> > > is given by 0.0, which occurs before the mutation and crossover
>> > > operations. For my problem, a genome with only zero entries is
>> > > invalid, so the algorithm cannot continue.
>> > >
>> > > Is it possible for me to avoid getting these zero genomes? If so, how?
>> > >
>> > > If you need any more information about what I am doing, I can try to
>> > > provide that.
>> > >
>> > > Thanks,
>> > > David
>> >
>> >
>> > Hi, David.
>> >
>> > Did you provide the genome with an initialization function? If not,
>> > GALib will use a default initialization, which (hopefully) initializes
>> > each gene of the genome with zero value. Quoting GALib's manual, "This
>> > operator does not actually create new genomes, rather it 'stuffs' the
>> > genomes with the primordial genetic material from which all solutions
>> > will evolve."
>>
>>
>> > When you create a GAPopulation or a GAGeneticAlgorithm object, you
>> > must pass a GAGenome object as argument. It is then cloned to create
>> > all the n population individuals. In other words, after that, all the
>> > individuals in the population are identical. The initialization
>> > function must be called for each individual so that they get diverse
>> > genetic material. Your initialization function must do some sort of
>> > variation in order to accomplish this, using, for example, random
>> > numbers.
>> >
>> >
>> > What may be happenning with your code is that you didn't provide an
>> > initialization function, and all the individuals are identical to the
>> > first one, which may have all its genes initializes to zero.
>> >
>> > In case this isn't your problem, a code snnipet may help to clarify things
>> >
>> >
>> > Good luck
>> >
>> >
>> > Anselmo
>>
>>
>> Ola Anselmo,
>>
>> A previous poster had asked about some code that I looked into and it
>> *appeared* (I haven't checked this against the source code yet) that in the
>> absence of an initializer, the genes were being set to their lower limit (at
>> least for the genome/ga combo he was using).
>>
>> Dave, unless you already have a good idea where the solution is, you want to
>> start out with as diverse a population as possible. If 50 people were to
>> look for a needle laying on the ground somewhere in a football field,
>> they'll find it faster if they start looking in random places than if they
>> all started looking in the same general location.
>>
>> Pete
>>
>> --
>> GPG Fingerprint: B9F1 6CF3 47C4 7CD8 D33E 70A9 A3B9 1945 67EA 951D
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>>
>> "A mathematician is a machine for converting coffee p at dirac.org
>> into theorems." -- Paul Erd?s http://www.dirac.org
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>
> Anselmo and Pete,
>
> Thanks for the replies. I do have the initializer defined, and it
> is working correctly as far as I can tell. I will post my main()
> and Initializer() below. I only get the genomes of 0 entries after
> the completion of the first generation of (correctly initialized)
> genomes, and before the mutation and crossover sequence begins. For
> the time being, I have simply amended my code so that the 0 genomes
> return a very bad objective value without being evaluated in the
> normal way. When I began to write this, I started with the code
> from ex1.C (as I recall) and modified it from there. The code that
> I have (anything specified in all caps is given by a #define):
>
> int main(int argc, char **argv) {
>
> for(int ii=1; ii genome( length, Objective );
> genome.initializer(::Initializer);
> genome.mutator(::Mutator);
> genome.crossover(::Crossover);
> genome.comparator(::Comparator);
>
> GASimpleGA ga(genome);
> ga.minimize();
> ga.nBestGenomes( 5 );
> ga.nConvergence( 10 );
> ga.populationSize(popsize);
> ga.nGenerations(ngen);
> ga.pMutation(pmut);
> ga.pCrossover(pcross);
>
> ga.selectScores( GAStatistics::AllScores );
> ga.scoreFrequency( 1 );
> ga.flushFrequency( 5 );
>
> ga.evolve();
>
> cout << "The GA found:\n" << ga.statistics() << "\n";
> cout << "The GA found:\n" << ga.statistics().bestPopulation() << "\n";
>
> return 0;
> }
>
> ------------------------------------------------------------------------------------------------
>
> void Initializer(GAGenome& g) {
> GA1DArrayGenome& genome = (GA1DArrayGenome&)g;
> int ii;
>
> static int n = 1;
> printf( "Inside Initializer, n = %d\n", n++ );
> float LayerNumber;
>
> int Sum = MULT_LENGTH;
> int Number = -1;
> int MaxInt = getlen( NUM_PIECEWISE_CONST_LAYERS, Sum, Number );
>
> LayerNumber = (float) GARandomInt(1, MaxInt);
> genome.gene( 0, LayerNumber );
> for( ii = 1; ii <= NUM_PIECEWISE_CONST_LAYERS; ii++ ) {
> genome.gene( ii, GARandomFloat( minwidth, maxwidth ) );
> }
>
> for( ii = NUM_PIECEWISE_CONST_LAYERS + 1; ii <
> NUM_PIECEWISE_CONST_LAYERS + 3; ii++ ) {
> genome.gene( ii, GARandomFloat( minwidth, maxwidth ) );
> }
>
> cout << genome << endl;
> }
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Hello, David,
There is something weird in your code. Are you sure it is compiling?
For example, the compiler should complain about the line:
GA1DArrayGenome& genome = (GA1DArrayGenome&)g;
since GA1DArrayGenome is a template class. The line should instead read :
GA1DArrayGenome<float>& genome = (GA1DArrayGenome<float>&)g;
Meanwhile, I could'n figure out why your genomes are being populated
with zeros.
What about the variable "minwidth"? Where its value comes from?
Good luck
Anselmo
Eng. Anselmo Pitombeira
Laboratório de Simulação e Controle
NUMA - Núcleo de Manufatura Avançada
Programa de Pós-Graduação em Engenharia Mecânica
EESC-USP
www.simulacao.eesc.sc.usp.br
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