Epsilon.java

//  Epsilon.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 jmetal.qualityIndicator ;

/**
 * This class implements the unary epsilon additive indicator as proposed in
 * E. Zitzler, E. Thiele, L. Laummanns, M., Fonseca, C., and Grunert da Fonseca.
 * V (2003): Performance Assesment of Multiobjective Optimizers: An Analysis and
 * Review. The code is the a Java version of the original metric implementation
 * by Eckart Zitzler.
 * It can be used also as a command line program just by typing
 * $java jmetal.qualityIndicator.Epsilon <solutionFrontFile> <trueFrontFile> <getNumberOfObjectives>
 */

public class Epsilon {

  /* stores the number of objectives */
  int     dim_   ;     
  /* obj_[i]=0 means objective i is to be minimized. This code always assume the minimization of all the objectives
   */
  int  [] obj_    ;     /* obj_[i] = 0 means objective i is to be minimized */
  /* method_ = 0 means apply additive epsilon and method_ = 1 means multiplicative
   * epsilon. This code always apply additive epsilon
   */
  int     method_; 
  /* stores a reference to  qualityIndicatorUtils */
  public jmetal.qualityIndicator.util.MetricsUtil utils_ = 
  		new jmetal.qualityIndicator.util.MetricsUtil();


  /**
   * Returns the epsilon indicator.
   * @param b True Pareto front
   * @param a Solution front
   * @return the value of the epsilon indicator
   */
  public double epsilon(double [][] b, double [][] a, int dim) {
    int  i, j, k;
    double  eps, eps_j = 0.0, eps_k=0.0, eps_temp;

    dim_ = dim ;
    set_params() ;
    
    if (method_ == 0)
      eps = Double.MIN_VALUE;
    else
      eps= 0;

    for (i = 0; i < a.length; i++) {
      for (j = 0; j < b.length; j++) {
        for (k = 0; k < dim_; k++) {
          switch (method_) {
            case 0:
              if (obj_[k] == 0)
                eps_temp = b[j][k] - a[i][k];                
                //eps_temp = b[j * dim_ + k] - a[i * dim_ + k];
              else
                eps_temp = a[i][k] - b[j][k];
                //eps_temp = a[i * dim_ + k] - b[j * dim_ + k];
              break;
            default:
              if ( (a[i][k] < 0 && b[j][k] > 0) ||
                   (a[i][k] > 0 && b[j][k] < 0) ||
                   (a[i][k] == 0 || b[j][k] == 0)) {
              //if ( (a[i * dim_ + k] < 0 && b[j * dim_ + k] > 0) ||
              //     (a[i * dim_ + k] > 0 && b[j * dim_ + k] < 0) ||
              //     (a[i * dim_ + k] == 0 || b[j * dim_ + k] == 0)) {
                System.err.println("error in data file");
                System.exit(0);
              }
              if (obj_[k] == 0)
                eps_temp = b[j][k] / a[i][k];
                //eps_temp = b[j * dim_ + k] / a[i * dim_ + k];
              else
                eps_temp = a[i][k] / b[j][k];
                //eps_temp = a[i * dim_ + k] / b[j * dim_ + k];
            break;
          }
          if (k == 0)
            eps_k = eps_temp;
          else if (eps_k < eps_temp)
            eps_k = eps_temp;
        }
        if (j == 0)
          eps_j = eps_k;
        else if (eps_j > eps_k)
          eps_j = eps_k;
      }
      if (i == 0)
        eps = eps_j;
      else if (eps < eps_j)
        eps = eps_j;
    }
    return eps;
  } // epsilon
 
  /**
   * Established the params by default
   */
  void  set_params() {
    int  i;
    obj_ = new int[dim_];
    for (i = 0; i < dim_; i++) {
      obj_[i] = 0;
    }
    method_ = 0;
  } // set_params
  
  
  /** 
  * Returns the additive-epsilon value of the paretoFront. This method call to the
  * calculate epsilon-indicator one
  */
  public static void main(String [] args) {
    double ind_value;
 
    if (args.length < 2) {
      System.err.println("Error using Epsilon. Type: \n java AdditiveEpsilon " +
                         "<FrontFile>" +
                         "<TrueFrontFile> + <getNumberOfObjectives>");
      System.exit(1);
    }
   
    Epsilon qualityIndicator = new Epsilon();
    double [][] solutionFront = qualityIndicator.utils_.readFront(args[0]);
    double [][] trueFront     = qualityIndicator.utils_.readFront(args[1]);
    //qualityIndicator.dim_ = trueParetoFront[0].length;
    //qualityIndicator.set_params();
            
    ind_value = qualityIndicator.epsilon(trueFront,
                                         solutionFront,
            new Integer(args[2]));
    
    System.out.println(ind_value);
  } // main
} // Epsilon