DTLZ1.java

//  DTLZ1.java
//
//  Author:
//       Antonio J. Nebro <antonio@lcc.uma.es>
//       Juan J. Durillo <durillo@lcc.uma.es>
//
//  Copyright (c) 2011 Antonio J. Nebro, Juan J. Durillo
//
//  This program is free software: you can redistribute it and/or modify
//  it under the terms of the GNU Lesser General Public License as published by
//  the Free Software Foundation, either version 3 of the License, or
//  (at your option) any later version.
//
//  This program is distributed in the hope that it will be useful,
//  but WITHOUT ANY WARRANTY; without even the implied warranty of
//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//  GNU Lesser General Public License for more details.
// 
//  You should have received a copy of the GNU Lesser General Public License
//  along with this program.  If not, see <http://www.gnu.org/licenses/>.

package org.uma.jmetal.problem.multiobjective.dtlz;

import org.uma.jmetal.problem.impl.AbstractDoubleProblem;
import org.uma.jmetal.solution.DoubleSolution;
import org.uma.jmetal.util.JMetalException;

import java.util.ArrayList;
import java.util.List;

/**
 * Class representing problem DTLZ1
 */
@SuppressWarnings("serial")
public class DTLZ1 extends AbstractDoubleProblem {
  /**
   * Creates a default DTLZ1 problem (7 variables and 3 objectives)
   */
  public DTLZ1() {
    this(7, 3);
  }

  /**
   * Creates a DTLZ1 problem instance
   *
   * @param numberOfVariables  Number of variables
   * @param numberOfObjectives Number of objective functions
   */
  public DTLZ1(Integer numberOfVariables, Integer numberOfObjectives) throws JMetalException {
    setNumberOfVariables(numberOfVariables);
    setNumberOfObjectives(numberOfObjectives);
    setName("DTLZ1");

    List<Double> lowerLimit = new ArrayList<>(getNumberOfVariables()) ;
    List<Double> upperLimit = new ArrayList<>(getNumberOfVariables()) ;

    for (int i = 0; i < getNumberOfVariables(); i++) {
      lowerLimit.add(0.0);
      upperLimit.add(1.0);
    }

    setLowerLimit(lowerLimit);
    setUpperLimit(upperLimit);
  }

  /** Evaluate() method */
  public void evaluate(DoubleSolution solution) {
    int numberOfVariables = getNumberOfVariables();
    int numberOfObjectives = getNumberOfObjectives() ;

    double[] f = new double[numberOfObjectives];
    double[] x = new double[numberOfVariables] ;

    int k = getNumberOfVariables() - getNumberOfObjectives() + 1;

    for (int i = 0; i < numberOfVariables; i++) {
      x[i] = solution.getVariableValue(i) ;
    }

    double g = 0.0;
    for (int i = numberOfVariables - k; i < numberOfVariables; i++) {
      g += (x[i] - 0.5) * (x[i] - 0.5) - Math.cos(20.0 * Math.PI * (x[i] - 0.5));
    }

    g = 100 * (k + g);
    for (int i = 0; i < numberOfObjectives; i++) {
      f[i] = (1.0 + g) * 0.5;
    }

    for (int i = 0; i < numberOfObjectives; i++) {
      for (int j = 0; j < numberOfObjectives - (i + 1); j++) {
        f[i] *= x[j];
      }
      if (i != 0) {
        int aux = numberOfObjectives - (i + 1);
        f[i] *= 1 - x[aux];
      }
    }

    for (int i = 0; i < numberOfObjectives; i++) {
      solution.setObjective(i, f[i]);
    }
  }
}