97 lines
3.1 KiB
C++
97 lines
3.1 KiB
C++
// -*- mode: c++; c-indent-level: 4; c++-member-init-indent: 8; comment-column: 35; -*-
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//-----------------------------------------------------------------------------
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// eoLottery.h
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// Implements the lottery procedure for selection
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// (c) GeNeura Team, 1998 - Marc Schoenauer, 2000
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/*
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2 of the License, or (at your option) any later version.
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This library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with this library; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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Contact: todos@geneura.ugr.es, http://geneura.ugr.es
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*/
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//-----------------------------------------------------------------------------
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#ifndef eoLottery_h
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#define eoLottery_h
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//-----------------------------------------------------------------------------
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#include <functional> //
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#include <numeric> // accumulate
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#include "eoPopOps.h"
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#include "eoRNG.h"
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//-----------------------------------------------------------------------------
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/// eoLottery: a selection method.
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/// requires EOT::Fitness to be float castable
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//-----------------------------------------------------------------------------
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template<class EOT> class eoLottery: public eoBinPopOp<EOT>
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{
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public:
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/// (Default) Constructor.
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eoLottery(const double & _rate = 1.0): rate(_rate) {}
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/** actually selects individuals from pop and put them into breeders
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* until breeders has the right size: rate*pop.size()
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* BUT what happens if breeders is already too big?
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*/
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void operator()( eoPop<EOT>& pop, eoPop<EOT>& breeders)
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{
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// scores of chromosomes
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vector<double> score(pop.size());
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// calculates total scores for chromosomes
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double total = 0;
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for (unsigned i = 0; i < pop.size(); i++) {
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score[i] = static_cast<double>(pop[i].fitness());
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total += score[i];
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}
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// number of offspring needed
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int target = (int)rint(rate * pop.size());
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// test of consistency
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if (breeders.size() >= target) {
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throw("Problem in eoLottery: already too many offspring");
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}
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// selection of chromosomes
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while (breeders.size() < target) {
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unsigned indloc = rng.roulette_wheel(score, total);
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breeders.push_back(pop[indloc]);
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}
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}
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/// accessor to private rate
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double Rate() {return rate;}
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/** @name Methods from eoObject */
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//@{
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/** readFrom and printOn inherited from eoMerge */
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/** Inherited from eoObject. Returns the class name.
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@see eoObject
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*/
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virtual string className() const {return "eoLottery";};
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//@}
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private:
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double rate; // selection rate
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};
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//-----------------------------------------------------------------------------
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#endif eoLottery_h
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