mutationswapsubtreeop.cpp

来自「非常好的进化算法EC 实现平台 可以实现多种算法 GA GP」· C++ 代码 · 共 478 行 · 第 1/2 页

/*
 *  Open BEAGLE
 *  Copyright (C) 2001-2005 by Christian Gagne and Marc Parizeau
 *
 *  This library 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 2.1 of the License, or (at your option) any later version.
 *
 *  This library 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 library; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 *  Contact:
 *  Laboratoire de Vision et Systemes Numeriques
 *  Departement de genie electrique et de genie informatique
 *  Universite Laval, Quebec, Canada, G1K 7P4
 *  http://vision.gel.ulaval.ca
 *
 */

/*!
 *  \file   beagle/GP/src/MutationSwapSubtreeOp.cpp
 *  \brief  Source code of class GP::MutationSwapSubtreeOp.
 *  \author Christian Gagne <[e-mail]>
 *  \author Jianjun Hu <[e-mail]>
 *  \author Marc Parizeau <[e-mail]>
 *  $Revision: 1.11 $
 *  $Date: 2005/10/04 16:25:10 $
 */

#include "beagle/GP.hpp"

#include <algorithm>
#include <string>

using namespace Beagle;


/*!
 *  \brief Construct a GP swap subtree mutation operator.
 *  \param inMutationPbName Mutation probability parameter name used in register.
 *  \param inDistribPbName Swap mutation distribution probability parameter name.
 *  \param inName Name of the operator.
 */
GP::MutationSwapSubtreeOp::MutationSwapSubtreeOp(Beagle::string inMutationPbName,
                                                 Beagle::string inDistribPbName,
                                                 Beagle::string inName) :
  Beagle::MutationOp(inMutationPbName, inName),
  mDistribPbName(inDistribPbName)
{ }


/*!
 *  \brief Initialize the GP swap subtree mutation operator.
 *  \param ioSystem System of the evolution.
 */
void GP::MutationSwapSubtreeOp::initialize(Beagle::System& ioSystem)
{
  Beagle_StackTraceBeginM();
  Beagle::MutationOp::initialize(ioSystem);
  if(ioSystem.getRegister().isRegistered(mMutationPbName)) {
    ioSystem.getRegister().deleteEntry(mMutationPbName);
  }

  if(ioSystem.getRegister().isRegistered(mMutationPbName)) {
    mMutationProba = castHandleT<Float>(ioSystem.getRegister()[mMutationPbName]);
  } else {
    mMutationProba = new Float(float(0.0));
    string lLongDescrip = "Swap subtree mutation probability for an individual. ";
    lLongDescrip += "A swap subtree mutation consists to swap two subtrees of a tree in an ";
    lLongDescrip += "individual.";
    Register::Description lProbaDescription(
      "Swap subtree mutation prob.",
      "Float",
      "0.0",
      lLongDescrip
    );
    ioSystem.getRegister().addEntry(mMutationPbName, mMutationProba, lProbaDescription);
  }

  if(ioSystem.getRegister().isRegistered(mDistribPbName)) {
    mDistributionProba = castHandleT<Float>(ioSystem.getRegister()[mDistribPbName]);
  } else {
    mDistributionProba = new Float(float(0.5));
    string lLongDescrip = "Probability that a swap subtree is internal ";
    lLongDescrip += "(the mutation occurs between three points, where the 2nd point is in the ";
    lLongDescrip += "1st point's subtree, and the 3rd point is in the 2nd point's subtree) vs ";
    lLongDescrip += "being external (the mutation occurs between two points, ";
    lLongDescrip += "where both points are not within the other's subtree). ";
    lLongDescrip += "Value of 1.0 means that the swap subtrees mutations are all internal ";
    lLongDescrip += "while value of 0.0 means that swap subtrees mutations are all external.";
    Register::Description lDescription(
      "Swap subtree mut. distrib. prob.",
      "Float",
      "0.5",
      lLongDescrip
    );
    ioSystem.getRegister().addEntry(mDistribPbName, mDistributionProba, lDescription);
  }

  if(ioSystem.getRegister().isRegistered("gp.tree.maxdepth")) {
    mMaxTreeDepth = castHandleT<UInt>(ioSystem.getRegister()["gp.tree.maxdepth"]);
  } else {
    mMaxTreeDepth = new UInt(17);
    Register::Description lDescription(
      "Maximum tree depth",
      "UInt",
      "17",
      "Maximum allowed depth for the trees."
    );
    ioSystem.getRegister().addEntry("gp.tree.maxdepth", mMaxTreeDepth, lDescription);
  }

  if(ioSystem.getRegister().isRegistered("gp.try")) {
    mNumberAttempts = castHandleT<UInt>(ioSystem.getRegister()["gp.try"]);
  } else {
    mNumberAttempts = new UInt(2);
    string lLongDescrip = "Maximum number of attempts to modify a GP tree in a genetic ";
    lLongDescrip += "operation. As there is topological constraints on GP trees (i.e. tree ";
    lLongDescrip += "depth limit), it is often necessary to try a genetic operation several times.";
    Register::Description lDescription(
      "Max number of attempts",
      "UInt",
      "2",
      lLongDescrip
    );
    ioSystem.getRegister().addEntry("gp.try", mNumberAttempts, lDescription);
  }
  Beagle_StackTraceEndM("void GP::MutationSwapSubtreeOp::initialize(Beagle::System& ioSystem)");
}


/*!
 *  \brief Swap subtree mutate a GP individual.
 *  \param ioIndividual GP individual to swap subtree mutate.
 *  \param ioContext Context of the evolution.
 */
bool GP::MutationSwapSubtreeOp::mutate(Beagle::Individual& ioIndividual, Beagle::Context& ioContext)
{
  Beagle_StackTraceBeginM();
  // Initial parameters checks.
  Beagle_AssertM(ioIndividual.size() > 0);
  Beagle_ValidateParameterM(mNumberAttempts->getWrappedValue()>0, "gp.try", ">0");

  // Cast method arguments.
  GP::Individual&     lGPIndiv      = castObjectT<GP::Individual&>(ioIndividual);
  GP::Context&        lContext1     = castObjectT<GP::Context&>(ioContext);
  GP::Context::Alloc& lContextAlloc =
    castObjectT<GP::Context::Alloc&>(ioContext.getSystem().getContextAllocator());
  GP::Context::Handle lContextHdl2  = castHandleT<GP::Context>(lContextAlloc.clone(lContext1));

  // Get parameters in local values, with the total number of nodes of the mutated individual.
  bool             lMatingDone     = false;
  float            lDistrProba     = mDistributionProba->getWrappedValue();
  unsigned int     lMaxTreeDepth   = mMaxTreeDepth->getWrappedValue();
  GP::Tree::Handle lOldTreeHandle1 = lContext1.getGenotypeHandle();
  unsigned int     lOldTreeIndex1  = lContext1.getGenotypeIndex();
  unsigned int     lSizeIndiv      = 0;
  for(unsigned int i=0; i<lGPIndiv.size(); ++i) lSizeIndiv += lGPIndiv[i]->size();

  // Some outputs.
  Beagle_LogDebugM(
    lContext1.getSystem().getLogger(),
    "mutation", "Beagle::GP::MutationSwapSubtreeOp",
    string("Individual tried for swap subtree mutation (before): ")+
    lGPIndiv.serialize()
  );

  // Mutation loop. Try the given number of attempts to mutation the individual.
  for(unsigned int lAttempt=0; lAttempt < mNumberAttempts->getWrappedValue(); lAttempt++) {

    // Calculate the number of nodes in the individual
    unsigned int lNbNodes = 0;
    for(unsigned int i=0; i<lGPIndiv.size(); i++) lNbNodes += lGPIndiv[i]->size();
    if(lNbNodes == 0) return false;

    // Choose a node of the individual to mutate.
    unsigned int lNode1 = lContext1.getSystem().getRandomizer().rollInteger(0, lNbNodes-1);      

    // Get the tree in which the choosen node is. Change the global node index to the tree's index.
    unsigned int lChoosenTree = 0;
    for(; lChoosenTree<lGPIndiv.size(); ++lChoosenTree) {
      if(lNode1 < lGPIndiv[lChoosenTree]->size()) break;
      Beagle_AssertM(lNode1 >= lGPIndiv[lChoosenTree]->size());
      lNode1 -= lGPIndiv[lChoosenTree]->size();
    }
    Beagle_AssertM(lChoosenTree < lGPIndiv.size());

    // Cannot do anything with an tree of size <= 1.
    if(lGPIndiv[lChoosenTree]->size() <= 1) continue;

    // Some outputs.
    Beagle_LogVerboseM(
      lContext1.getSystem().getLogger(),
      "mutation", "Beagle::GP::MutationSwapSubtreeOp",
      string("Trying a swap subtree mutation of the ")+uint2ordinal(lChoosenTree+1)+
      string(" tree")
    );

    // Make two clones of the choosen tree.
    GP::Tree::Alloc& lTreeAlloc  = castObjectT<GP::Tree::Alloc&>(*lGPIndiv.getTypeAlloc());
    GP::Tree::Handle lTreeClone1 = castHandleT<GP::Tree>(lTreeAlloc.clone(*lGPIndiv[lChoosenTree]));
    GP::Tree::Handle lTreeClone2 = castHandleT<GP::Tree>(lTreeAlloc.clone(*lGPIndiv[lChoosenTree]));

    // Now we decide whether the swap subtree mutation is internal or external.
    bool lMutationType = lContext1.getSystem().getRandomizer().rollUniform(0.0, 1.0) < lDistrProba;

    // Cannot do an internal mutation when there is only one branch in the tree.
    if(lTreeClone1->size() == (*lTreeClone1)[0].mPrimitive->getNumberArguments()+1)
      lMutationType = false;

    // This is special case, a linear tree. Cannot do an external mutation.
    if(lTreeClone1->size() == (*lTreeClone1)[1].mSubTreeSize+1) {
      if(lTreeClone1->size()==2) continue;   // Cannot do anything here with the tree.
      lMutationType = true;
    }

    // lMutationType is true -> internal mutation
    if(lMutationType)  {

      // If the selected node is a terminal, or a branch with a subtree made only of terminals,
      // choose another node in the same tree.
      while((*lTreeClone1)[lNode1].mSubTreeSize ==
            ((*lTreeClone1)[lNode1].mPrimitive->getNumberArguments()+1)) {
        lNode1 = lContext1.getSystem().getRandomizer().rollInteger(0, lTreeClone1->size()-1);
      }

      // Choosing the second node, a branch in lNode1's subtree.
      unsigned int lSubTreeSizeN1 = (*lTreeClone1)[lNode1].mSubTreeSize;
      unsigned int lN2OffN1 =
        lContext1.getSystem().getRandomizer().rollInteger(1, lSubTreeSizeN1-1);
      unsigned int lNode2 = lNode1 + lN2OffN1;
      while((*lTreeClone1)[lNode2].mPrimitive->getNumberArguments() == 0) {