WFG2.java

//  WFG2.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.problems.WFG;

import jmetal.core.Solution;
import jmetal.core.Variable;
import jmetal.util.JMException;

/**
 * This class implements the WFG2 problem
 * Reference: Simon Huband, Luigi Barone, Lyndon While, Phil Hingston
 *            A Scalable Multi-objective Test Problem Toolkit.
 *            Evolutionary Multi-Criterion Optimization: 
 *            Third International Conference, EMO 2005. 
 *            Proceedings, volume 3410 of Lecture Notes in Computer Science
 */
public class WFG2 extends WFG{
    
 /**
  * Creates a default WFG2 instance with 
  * 2 position-related parameters 
  * 4 distance-related parameters
  * and 2 objectives
  * @param solutionType The solution type must "Real" or "BinaryReal".
  */
  public WFG2(String solutionType) throws ClassNotFoundException {
    this(solutionType, 2, 4, 2) ;
  } // WFG2

 /**
  * Creates a WFG2 problem instance
  * @param k Number of position parameters
  * @param l Number of distance parameters
  * @param M Number of objective functions
  * @param solutionType The solution type must "Real" or "BinaryReal".
  */
  public WFG2(String solutionType, Integer k, Integer l, Integer M) throws ClassNotFoundException {
    super(solutionType, k,l,M);
    problemName_ = "WFG2";
        
    S_ = new int[M_];
    for (int i = 0; i < M_; i++) {
      S_[i] = 2 * (i+1);
    }
        
    A_ = new int[M_-1];        
    for (int i = 0; i < M_-1; i++) {
      A_[i] = 1;          
    }        
  } // WFG2          
    
  /** 
  * Evaluates a solution 
  * @param z The solution to evaluate
  * @return double [] with the evaluation results
  */    
  public float [] evaluate(float [] z){                
    float [] y;
        
    y = normalise(z);        
    y = t1(y,k_);
    y = t2(y,k_);        
    y = t3(y,k_,M_);    
        
    float [] result = new float[M_];
    float [] x = calculate_x(y);
    for (int m = 1; m <= M_ - 1 ; m++) {
      result [m-1] = D_*x[M_-1] + S_[m-1] * (new Shapes()).convex(x,m);
    }        
    result[M_-1] = D_*x[M_-1] + S_[M_-1] * (new Shapes()).disc(x,5,(float)1.0,(float)1.0);
    
    return result;
  } // evaluate
    

  /**
   * WFG2 t1 transformation
   */  
  public float [] t1(float [] z, int k){
    float [] result = new float[z.length];

    System.arraycopy(z, 0, result, 0, k);
        
    for (int i = k; i < z.length; i++) {
      result[i] = (new Transformations()).s_linear(z[i],(float)0.35);
    }
        
    return result;      
  } // t1
    
  /**
   * WFG2 t2 transformation
   */
  public float [] t2(float [] z, int k){
    float [] result = new float[z.length];

    System.arraycopy(z, 0, result, 0, k);
        
    int l = z.length - k;
        
    for (int i = k+1; i <= k + l/2; i++){
      int head = k + 2*(i - k) - 1;
      int tail = k + 2*(i - k);              
      float [] subZ = subVector(z,head-1,tail-1);
      
      result[i-1] = (new Transformations()).r_nonsep(subZ,2);
    }
        
    return result;
  } // t2
       
  /**
   * WFG2 t3 transformation
   */  
  public float [] t3(float [] z, int k, int M){
    float [] result = new float[M];
    float [] w      = new float[z.length];
        
        
    for (int i = 0; i < z.length; i++) {
      w[i] = (float)1.0;
    }
        
    for (int i = 1; i <= M-1; i++){
      int head = (i - 1)*k/(M-1) + 1;
      int tail = i * k / (M - 1);                                   
      float [] subZ = subVector(z,head-1,tail-1);
      float [] subW = subVector(w,head-1,tail-1);
            
      result[i-1] = (new Transformations()).r_sum(subZ,subW);            
    }
        
    int l = z.length - k;
    int head = k + 1;
    int tail = k + l / 2;
              
    float [] subZ = subVector(z,head-1,tail-1);      
    float [] subW = subVector(w,head-1,tail-1);        
    result[M-1] = (new Transformations()).r_sum(subZ,subW);
                
    return result;
  } // t3
 
  /** 
  * Evaluates a solution 
  * @param solution The solution to evaluate
   * @throws JMException 
  */ 
  public final void evaluate(Solution solution) throws JMException {
    float [] variables = new float[getNumberOfVariables()];
    Variable[] dv = solution.getDecisionVariables();
        
    for (int i = 0; i < getNumberOfVariables(); i++) {
      variables[i] = (float)dv[i].getValue();    
    }
        
    float [] sol = evaluate(variables);
        
    for (int i = 0; i < sol.length; i++) {
      solution.setObjective(i,sol[i]);
    }
  } // evaluate
} // WFG2