Exemplo n.º 1
0
 private double computeFitness(IGPProgram a_program, Variable vx) {
   double error = 0.0f;
   Object[] noargs = new Object[0];
   // Initialize local stores.
   // ------------------------
   a_program.getGPConfiguration().clearStack();
   a_program.getGPConfiguration().clearMemory();
   // Compute fitness for each program.
   // ---------------------------------
   for (int i = 2; i < 15; i++) {
     for (int j = 0; j < a_program.size(); j++) {
       vx.set(new Integer(i));
       try {
         try {
           // Only evaluate after whole GP program was run.
           // ---------------------------------------------
           if (j == a_program.size() - 1) {
             double result = a_program.execute_int(j, noargs);
             error += Math.abs(result - fib_iter(i));
           } else {
             a_program.execute_void(j, noargs);
           }
         } catch (IllegalStateException iex) {
           error = Double.MAX_VALUE / 2;
           break;
         }
       } catch (ArithmeticException ex) {
         System.out.println("Arithmetic Exception with x = " + i);
         System.out.println(a_program.getChromosome(j));
         throw ex;
       }
     }
   }
   return error;
 }
Exemplo n.º 2
0
 /**
  * Find and print the solution, return the solution error.
  *
  * @param a_conf the configuration to use
  * @return absolute difference between the required and computed change
  */
 protected int solve(
     Configuration a_conf,
     int a_targetChangeAmount,
     SupergeneChangeFitnessFunction a_fitnessFunction,
     Gene[] a_sampleGenes)
     throws InvalidConfigurationException {
   IChromosome sampleChromosome = new Chromosome(a_conf, a_sampleGenes);
   a_conf.setSampleChromosome(sampleChromosome);
   // Finally, we need to tell the Configuration object how many
   // Chromosomes we want in our population. The more Chromosomes,
   // the larger number of potential solutions (which is good for
   // finding the answer), but the longer it will take to evolve
   // the population (which could be seen as bad). We'll just set
   // the population size to 500 here.
   // ------------------------------------------------------------
   a_conf.setPopulationSize(POPULATION_SIZE);
   // Create random initial population of Chromosomes.
   // ------------------------------------------------
   Genotype population = Genotype.randomInitialGenotype(a_conf);
   int s;
   Evolution:
   // Evolve the population, break if the the change solution is found.
   // -----------------------------------------------------------------
   for (int i = 0; i < MAX_ALLOWED_EVOLUTIONS; i++) {
     population.evolve();
     s =
         Math.abs(
             a_fitnessFunction.amountOfChange(population.getFittestChromosome())
                 - a_targetChangeAmount);
     if (s == 0) {
       break Evolution;
     }
   }
   // Display the best solution we found.
   // -----------------------------------
   IChromosome bestSolutionSoFar = report(a_fitnessFunction, population);
   return Math.abs(a_fitnessFunction.amountOfChange(bestSolutionSoFar) - a_targetChangeAmount);
 }
  /**
   * Executes the genetic algorithm to determine the minimum number of items necessary to make up
   * the given target volume. The solution will then be written to the console.
   *
   * @param a_knapsackVolume the target volume for which this method is attempting to produce the
   *     optimal list of items
   * @throws Exception
   * @author Klaus Meffert
   * @since 2.3
   */
  public static void findItemsForVolume(double a_knapsackVolume) throws Exception {
    // Start with a DefaultConfiguration, which comes setup with the
    // most common settings.
    // -------------------------------------------------------------
    Configuration conf = new DefaultConfiguration();
    conf.setPreservFittestIndividual(true);
    // Set the fitness function we want to use. We construct it with
    // the target volume passed in to this method.
    // ---------------------------------------------------------
    FitnessFunction myFunc = new KnapsackFitnessFunction(a_knapsackVolume);
    conf.setFitnessFunction(myFunc);
    // Now we need to tell the Configuration object how we want our
    // Chromosomes to be setup. We do that by actually creating a
    // sample Chromosome and then setting it on the Configuration
    // object. As mentioned earlier, we want our Chromosomes to each
    // have as many genes as there are different items available. We want the
    // values (alleles) of those genes to be integers, which represent
    // how many items of that type we have. We therefore use the
    // IntegerGene class to represent each of the genes. That class
    // also lets us specify a lower and upper bound, which we set
    // to senseful values (i.e. maximum possible) for each item type.
    // --------------------------------------------------------------
    Gene[] sampleGenes = new Gene[itemVolumes.length];
    for (int i = 0; i < itemVolumes.length; i++) {
      sampleGenes[i] = new IntegerGene(conf, 0, (int) Math.ceil(a_knapsackVolume / itemVolumes[i]));
    }
    IChromosome sampleChromosome = new Chromosome(conf, sampleGenes);
    conf.setSampleChromosome(sampleChromosome);
    // Finally, we need to tell the Configuration object how many
    // Chromosomes we want in our population. The more Chromosomes,
    // the larger number of potential solutions (which is good for
    // finding the answer), but the longer it will take to evolve
    // the population (which could be seen as bad).
    // ------------------------------------------------------------
    conf.setPopulationSize(50);
    // Create random initial population of Chromosomes.
    // Here we try to read in a previous run via XMLManager.readFile(..)
    // for demonstration purpose!
    // -----------------------------------------------------------------
    Genotype population;
    try {
      Document doc = XMLManager.readFile(new File("knapsackJGAP.xml"));
      population = XMLManager.getGenotypeFromDocument(conf, doc);
    } catch (FileNotFoundException fex) {
      population = Genotype.randomInitialGenotype(conf);
    }
    population = Genotype.randomInitialGenotype(conf);
    // Evolve the population. Since we don't know what the best answer
    // is going to be, we just evolve the max number of times.
    // ---------------------------------------------------------------
    for (int i = 0; i < MAX_ALLOWED_EVOLUTIONS; i++) {
      population.evolve();
    }
    // Save progress to file. A new run of this example will then be able to
    // resume where it stopped before!
    // ---------------------------------------------------------------------

    // represent Genotype as tree with elements Chromomes and Genes
    // ------------------------------------------------------------
    DataTreeBuilder builder = DataTreeBuilder.getInstance();
    IDataCreators doc2 = builder.representGenotypeAsDocument(population);
    // create XML document from generated tree
    // ---------------------------------------
    XMLDocumentBuilder docbuilder = new XMLDocumentBuilder();
    Document xmlDoc = (Document) docbuilder.buildDocument(doc2);
    XMLManager.writeFile(xmlDoc, new File("knapsackJGAP.xml"));
    // Display the best solution we found.
    // -----------------------------------
    IChromosome bestSolutionSoFar = population.getFittestChromosome();
    System.out.println(
        "The best solution has a fitness value of " + bestSolutionSoFar.getFitnessValue());
    System.out.println("It contained the following: ");
    int count;
    double totalVolume = 0.0d;
    for (int i = 0; i < bestSolutionSoFar.size(); i++) {
      count = ((Integer) bestSolutionSoFar.getGene(i).getAllele()).intValue();
      if (count > 0) {
        System.out.println("\t " + count + " x " + itemNames[i]);
        totalVolume += itemVolumes[i] * count;
      }
    }
    System.out.println("\nFor a total volume of " + totalVolume + " ccm");
    System.out.println("Expected volume was " + a_knapsackVolume + " ccm");
    System.out.println("Volume difference is " + Math.abs(totalVolume - a_knapsackVolume) + " ccm");
  }