terminal.java

JGAP（发音"jay-gap"）是一款用Java编写的遗传算法包。提供了基本的遗传算法.你可以使用它来解决一些适用于遗传算法解决的问题.

/*
 * This file is part of JGAP.
 *
 * JGAP offers a dual license model containing the LGPL as well as the MPL.
 *
 * For licencing information please see the file license.txt included with JGAP
 * or have a look at the top of class org.jgap.Chromosome which representatively
 * includes the JGAP license policy applicable for any file delivered with JGAP.
 */
package org.jgap.gp.terminal;

import org.jgap.gp.*;
import org.jgap.*;
import org.jgap.gp.impl.*;

/**
 * A terminal is a static number that can be mutated.
 *
 * @author Klaus Meffert
 * @since 3.0
 */
public class Terminal
    extends CommandGene implements IMutateable {
  /** String containing the CVS revision. Read out via reflection!*/
  private static final String CVS_REVISION = "$Revision: 1.6 $";

  private String m_value;

  private double m_lowerBounds;

  private double m_upperBounds;

  public Terminal()
      throws InvalidConfigurationException {
    this(GPGenotype.getGPConfiguration(), CommandGene.IntegerClass);
  }

  public Terminal(final GPConfiguration a_conf, Class a_returnType)
      throws InvalidConfigurationException {
    this(a_conf, a_returnType, 0d, 99d);
  }

  public Terminal(final GPConfiguration a_conf, Class a_returnType,
                  double a_minValue, double a_maxValue)
      throws InvalidConfigurationException {
    super(a_conf, 0, a_returnType);
    m_lowerBounds = a_minValue;
    m_upperBounds = a_maxValue;
    setRandomValue();
  }

  protected void setRandomValue() {
    RandomGenerator randomGen = getGPConfiguration().getRandomGenerator();
    m_value = new Long(Math.round(randomGen.nextDouble() *
                                  (m_upperBounds - m_lowerBounds) +
                                  m_lowerBounds)).toString();
  }

  protected CommandGene newGeneInternal() {
    try {
      return new Terminal(getGPConfiguration(), getReturnType());
    } catch (InvalidConfigurationException iex) {
      throw new IllegalStateException(iex.getMessage());
    }
  }

  public void setValue(double a_value) {
    if (isIntegerType()) {
      m_value = new Long(Math.round(a_value)).toString();
    }
    else if (isFloatType()) {
      m_value = Double.toString(a_value);
    }
    else {
      throw new UnsupportedOperationException("Setting a value for type "
          + getReturnType()
          + " is not supported with Terminal!");
    }
  }

  public void applyMutation(int index, double a_percentage) {
    // If very high then do mutation not relying on current value
    // random value.
    // ----------------------------------------------------------
    if (a_percentage > 0.85d) {
      setRandomValue();
    }
    else {
      double range = (m_upperBounds - m_lowerBounds) * a_percentage;
      double newValue;
      double value = Double.parseDouble(m_value);
      if (value >= (m_upperBounds - m_lowerBounds) / 2) {
        newValue = value -
            getGPConfiguration().getRandomGenerator().nextDouble() * range;
      }
      else {
        newValue = value +
            getGPConfiguration().getRandomGenerator().nextDouble() * range;
      }
      // Ensure value is within bounds.
      // ------------------------------
      if (newValue < m_lowerBounds || newValue > m_upperBounds) {
        setRandomValue();
      }
      else {
        setValue(newValue);
      }
    }
  }

  public String toString() {
    return m_value;
  }

  public int execute_int(ProgramChromosome c, int n, Object[] args) {
    return Integer.parseInt( (String) m_value);
  }

  public long execute_long(ProgramChromosome c, int n, Object[] args) {
    return Long.parseLong( (String) m_value);
  }

  public float execute_float(ProgramChromosome c, int n, Object[] args) {
    return Float.parseFloat( (String) m_value);
  }

  public double execute_double(ProgramChromosome c, int n, Object[] args) {
    return Double.parseDouble(m_value);
  }

  public Class getChildType(IGPProgram a_ind, int a_chromNum) {
    return null;
  }
}