differentialevolutionselection.java

关于多目标优化的代码

/**
 * DifferentialEvolutionSelection.java
 * Class representing the selection operator used in differential evolution
 * @author Antonio J. Nebro
 * @version 1.0
 */
package jmetal.base.operator.selection;

import jmetal.base.Configuration;
import jmetal.base.Operator;
import jmetal.base.Solution;
import jmetal.base.SolutionSet;
import jmetal.base.Configuration.SolutionType_;
import jmetal.util.JMException;
import jmetal.util.PseudoRandom;

public class DifferentialEvolutionSelection extends Operator {


  /**
   * Constructor
   */
  DifferentialEvolutionSelection() {
  } // Constructor

  /**
   * Executes the operation
   * @param object An object containing the population and the position (index)
   *               of the current individual
   * @return An object containing the three selected parents
   */
  public Object execute(Object object) throws JMException {
    Object[] parameters = (Object[])object ;
    SolutionSet population = (SolutionSet)parameters[0];
    int         index      = (Integer)parameters[1] ;

    Solution[] parents = new Solution[3] ;
    int r1, r2, r3 ;

    if (population.size() < 4)
      throw new JMException("DifferentialEvolutionSelection: the population has less than four solutions") ;

    do {
      r1 = (int)(PseudoRandom.randInt(0,population.size()-1));
    } while( r1==index );
    do {
      r2 = (int)(PseudoRandom.randInt(0,population.size()-1));
    } while( r2==index || r2==r1);
    do {
      r3 = (int)(PseudoRandom.randInt(0,population.size()-1));
    } while( r3==index || r3==r1 || r3==r2 );

    parents[0] = population.get(r1) ;
    parents[1] = population.get(r2) ;
    parents[2] = population.get(r3) ;

    return parents ;
  } // execute
} // DifferentialEvolutionSelection