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File org.dgpf.search.algorithms.ga.selection.RoundRobinSelection.java

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/*
 * Copyright (c) 2006 Thomas Weise
 *
 * E-Mail           : tweise@gmx.de
 * Creation Date    : 2006-04-10 15:46:38
 * Original Filename: org.search.algorithms.dgpf.ga.selection.RoundRobinSelection.java
 * Version          : 2.0.4
 * Last modification: 2006-06-03
 *                by: Thomas Weise
 *
 * License          : GNU LESSER GENERAL PUBLIC LICENSE
 *                    Version 2.1, February 1999
 *                    You should have received a copy of this license along
 *                    with this library; if not, write to the Free Software
 *                    Foundation, Inc., 59 Temple Place, Suite 330, Boston,
 *                    MA 02111-1307, USA or download the license under
 *                    http://www.gnu.org/copyleft/lesser.html.
 *
 * Warranty         : This software is provided "as is" 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.
 */


package org.dgpf.search.algorithms.ga.selection;

import java.io.Serializable;

import org.dgpf.search.algorithms.ga.SelectionAlgorithm;
import org.dgpf.search.algorithms.ga.SortingAlgorithm;
import org.dgpf.search.api.Individual;
import org.dgpf.search.api.SearchState;
import org.dgpf.search.api.adaptation.DefaultSearchAdapter;
import org.sfc.math.stochastic.Randomizer;

/**
 * This selection algorithm performs basically a round robin of other
 * selection algorithms it's hosting.
 *
 *
 * @author Thomas Weise
 */

public final class RoundRobinSelection extends SelectionAlgorithm
  {
/**
 * The serial version uid.
 */

  private   static  final long    serialVersionUID        = 1;

/**
 * The selection algorithms used internally.
 */

  private   static  final SelectionAlgorithm[]  CONFIG  =
   new SelectionAlgorithm[] { new TournamentSelection(7),
                                  RankedSelection.DEFAULT_INSTANCE,
                              new OrderedSelection(5.0d) };
/**
 * The default modulo.
 */

  private   static  final int                   DEFAULT_MODULO  =
     ((int)(Math.max(
        ((DefaultSearchAdapter.DEFAULT_UPDATE_THRESHOLD/
            (3*CONFIG.length))), 10)));

/**
 * The index of the selection algorithm currently used.
 */

  private volatile  int                             m_index ;
/**
 * The modulo for changing the selection algorithm.
 */

  private volatile  int                             m_modulo  ;
/**
 * The selection algorithms to be used.
 */

  private           SelectionAlgorithm[]            m_select  ;
/**
 * The base modulo.
 */

  private final     int                             m_base_modulo ;
/**
 * The current selection algorithm.
 */

  private volatile  SelectionAlgorithm              m_sa;

/**
 * Create a new instance of the round robin selection.
 */

  public  RoundRobinSelection()
    {
    this(-1, null);
    }
  
  
/**
 * Create a new instance of the round robin selection.
 * @param p_modulo    The modulo to use for the round robin selection.
 * @param p_selection The selection algorithms to alternate between.
 */

  public  RoundRobinSelection(final int                   p_modulo,
                              final SelectionAlgorithm[]  p_selection)
    {
    super(null);
    this.m_select = (((p_selection != null) && (p_selection.length > 0)) ?
                      p_selection : CONFIG);
    this.m_modulo = ((p_modulo > 0) ? p_modulo : DEFAULT_MODULO);
    this.m_base_modulo = this.m_modulo;
    this.m_sa = p_selection[0];
    }

/**
 * This method will be called by the search engine whenever it feels like
 * it is time to adapt the current search parameters to the current search
 * state. If you override this method, you must also declare your class
 * as instance of <code>ICloneable</code>.
 * @param p_state The current state of the search.
 * @return  <code>true</code> if and only if the update level should be
 *          resetted, <code>false</code> if everything should continue
 *          normal.
 */

  @Override
  protected final boolean  adapt (final SearchState<?> p_state)
    {
    long l_i;

    if(super.adapt(p_state)) return true;

    l_i = p_state.get_update_level();

    if( (l_i % this.m_modulo) == 0 )
      {
      this.m_index++;
      if(this.m_index >= this.m_select.length)
        {
        this.m_modulo++;
        this.m_index = 0;
        }
      this.m_sa = this.m_select[this.m_index];
      }

    return false;
    }


/**
 * This method will be called whenever the search parameters perform a
 * reset, meaning that the search level is set back to 0.
 */

  @Override
  protected final void  reset ()
    {
    super.reset();
    this.m_modulo = this.m_base_modulo;
    this.m_index  = 0;
    }
  
/**
 * Select one individual out of the population for reproduction (crossover
 * or mutation). The individuals in the array are ordered by the search's
 * current comparator, with the fittest individual at index <code>0</code>
 * and the worst at index <code>p_count-1</code>.
 * @param p_random        The randomizer to be used for the selection.
 * @param p_individuals   The population of individuals after being
 *                        preprocessed.
 * @param p_count         The count of valid items inside the population
 *                        array.
 * @param <Genotype>      The genotype of the individuals to select.
 * @return  An individual to reproduce.
 */

  @Override
  public  final  <Genotype extends Serializable> Individual<Genotype>
                         select(final Randomizer             p_random,
                                final Individual<Genotype>[] p_individuals,
                                final int                    p_count)
    {    
    return this.m_sa.select(p_random, p_individuals, p_count);
    }


/**
 * Returns unique, textual identifier of this genetic selection algorithm.
 * @return The unique, textual identifier of this genetic selection
 *         algorithm.
 */

  @Override
  public  final String  toString  ()
    {
    return super.toString() + '(' + this.m_sa.toString() + ')';
    }
  
/**
 * Obtain the sorting algorithm to be applied before selecting.
 * @return The sorting algorithm to be applied before selecting.
 */

  @Override
  public  final SortingAlgorithm  get_sorting_algorithm()
    {
    return this.m_sa.get_sorting_algorithm();
    }

/**
 * Check whether this object equals another one. This method is internally
 * invoked by <code>equals()</code>. 
 * @param p_object  The object to compare with.
 * @return <code>true</code> if and only if this object equals to the other
 *         one.
 */

  @Override
  protected final boolean is_equal  (final Object p_object)
    {
    RoundRobinSelection   l_r;
    SelectionAlgorithm[]  l_a, l_b;
    int                   l_i;
    
    if(p_object instanceof RoundRobinSelection)
      {
      l_r = ((RoundRobinSelection)p_object);
      
      if( (l_r.m_index       == this.m_index)  &&
          (l_r.m_modulo      == this.m_modulo) &&
          (l_r.m_base_modulo == this.m_base_modulo) )
        {
        l_a = this.m_select;
        l_b = l_r.m_select;
        
        l_i = l_a.length;
        if(l_i == l_b.length)
          {
          for(--l_i; l_i >= 0; l_i--)
            {
            if(!(l_a[l_i].equals(l_b[l_i])))
              {
              return false;
              }
            }
          
          return true;
          }
        }
      }
    
    return false;
    }
  }

File Information:

file name:RoundRobinSelection.java
package:org.dgpf.search.algorithms.ga.selection
qualified name:org.dgpf.search.algorithms.ga.selection.RoundRobinSelection.java
file type:Java Source File
download location:download http://dgpf.sourceforge.net/source/org/dgpf/search/algorithms/ga/selection/RoundRobinSelection.java
size:7.635 KB (7819 B)
uploaded: 2015-07-22 04:10:59 GMT+0000
last update: 2006-06-04 11:20:50 GMT+0000
last access: 2017-11-24 00:13:35 GMT+0000

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