Example #1
0
/*!
 *  \brief Apply the operation on a deme in the given context.
 *  \param ioDeme Reference to the deme on which the operation takes place.
 *  \param ioContext Evolutionary context of the operation.
 */
void GenerationalOp::operate(Deme& ioDeme, Context& ioContext)
{
    Beagle_StackTraceBeginM();
    Beagle_NonNullPointerAssertM(getRootNode());
    Beagle_NonNullPointerAssertM(mElitismKeepSize);
    Beagle_ValidateParameterM(mElitismKeepSize->getWrappedValue() <= ioDeme.size(),
                              "ec.elite.keepsize",
                              "The elistism keepsize must be less than the deme size!");

    Beagle_LogTraceM(
        ioContext.getSystem().getLogger(),
        "Processing using generational replacement strategy the " <<
        uint2ordinal(ioContext.getDemeIndex()+1) << " deme"
    );
    Beagle_LogTraceM(ioContext.getSystem().getLogger(), (*this));

    RouletteT<unsigned int> lRoulette;
    buildRoulette(lRoulette, ioContext);

    Individual::Bag lOffsprings;
    const Factory& lFactory = ioContext.getSystem().getFactory();
    if(mElitismKeepSize->getWrappedValue() > 0) {
        History::Handle lHistory = castHandleT<History>(ioContext.getSystem().haveComponent("History"));
        std::make_heap(ioDeme.begin(), ioDeme.end(), IsLessPointerPredicate());
        for(unsigned int i=0; i<mElitismKeepSize->getWrappedValue(); ++i) {
            std::string lIndividualType = ioDeme[0]->getType();
            Individual::Alloc::Handle lIndividualAlloc =
                castHandleT<Individual::Alloc>(lFactory.getAllocator(lIndividualType));
            Individual::Handle lEliteIndiv = castHandleT<Individual>(lIndividualAlloc->allocate());
            lEliteIndiv->copy(*ioDeme[0], ioContext.getSystem());
            lOffsprings.push_back(lEliteIndiv);
            if(lHistory != NULL) {
                HistoryID::Handle lHID = castHandleT<HistoryID>(ioDeme[0]->getMember("HistoryID"));
                std::vector<HistoryID> lParent;
                if(lHID != NULL) lParent.push_back(*lHID);
                lHistory->allocateNewID(*lEliteIndiv);
                lHistory->trace(ioContext, lParent, lEliteIndiv, getName(), "elitism");
            }
            std::pop_heap(ioDeme.begin(), (ioDeme.end()-i), IsLessPointerPredicate());
        }
    }

    for(unsigned int i=mElitismKeepSize->getWrappedValue(); i<ioDeme.size(); ++i) {
        unsigned int lIndexBreeder = lRoulette.select(ioContext.getSystem().getRandomizer());
        BreederNode::Handle lSelectedBreeder=getRootNode();
        for(unsigned int j=0; j<lIndexBreeder; ++j)
            lSelectedBreeder=lSelectedBreeder->getNextSibling();
        Beagle_NonNullPointerAssertM(lSelectedBreeder);
        Beagle_NonNullPointerAssertM(lSelectedBreeder->getBreederOp());
        Individual::Handle lBredIndiv =
            lSelectedBreeder->getBreederOp()->breed(ioDeme, lSelectedBreeder->getFirstChild(), ioContext);
        Beagle_NonNullPointerAssertM(lBredIndiv);
        lOffsprings.push_back(lBredIndiv);
    }

    for(unsigned int j=0; j<lOffsprings.size(); ++j) ioDeme[j] = lOffsprings[j];
    Beagle_StackTraceEndM();
}
Example #2
0
/*!
 *  \brief Apply NSGA2 multiobjective selection operator as a standard operator.
 *  \param ioDeme Deme on which selection operator is applied.
 *  \param ioContext Evolutionary context.
 */
void EMO::NSGA2Op::applyAsStandardOperator(Deme& ioDeme, Context& ioContext)
{
	Beagle_StackTraceBeginM();
	// Fast non-dominated sorting, followed by insertion of the first Pareto fronts.
	Beagle_LogVerboseM(
	    ioContext.getSystem().getLogger(),
	    "Applying fast non-dominated sorting on the whole population"
	);
	NSGA2Op::Fronts lParetoFronts;
	const unsigned int lDesiredPopSize = (*mPopSize)[ioContext.getDemeIndex()];
	Individual::Bag lSortedPop(ioDeme);
	sortFastND(lParetoFronts, lDesiredPopSize, lSortedPop, ioContext);
	unsigned int lIndexDeme=0;
	for(unsigned int j=0; j<(lParetoFronts.size()-1); ++j) {
		for(unsigned int k=0; k<lParetoFronts[j].size(); ++k) {
			ioDeme[lIndexDeme++] = lSortedPop[lParetoFronts[j][k]];
		}
	}

	// Insertion of the last Pareto front, using crowding distance
	Individual::Bag lLastFrontIndiv;
	for(unsigned int l=0; l<lParetoFronts.back().size(); ++l) {
		lLastFrontIndiv.push_back(lSortedPop[lParetoFronts.back()[l]]);
	}
	NSGA2Op::Distances lDistances;
	Beagle_LogVerboseM(
	    ioContext.getSystem().getLogger(),
	    "Computing crowding distance on the " << uint2ordinal(lParetoFronts.size()) <<
	    " Pareto front, which is made of " << uint2ordinal(lParetoFronts.back().size()) << " individuals"
	);
	evalCrowdingDistance(lDistances, lLastFrontIndiv);
	for(unsigned int m=0; lIndexDeme<lDesiredPopSize; ++m) {
		ioDeme[lIndexDeme++] = lLastFrontIndiv[lDistances[m].second];
	}
	ioDeme.resize(lDesiredPopSize);
	Beagle_StackTraceEndM();
}
/*!
 *  \brief Apply the decimation operation on the deme.
 *  \param ioDeme Current deme of individuals to decimate.
 *  \param ioContext Context of the evolution.
 */
void DecimateOp::operate(Deme& ioDeme, Context& ioContext)
{
	Beagle_StackTraceBeginM();
	Beagle_ValidateParameterM((mDecimationRatio->getWrappedValue()<=1.0),
	                          mDecimationRatioName,
	                          "The decimation ratio must be less than or equal to 1.0.");

	Beagle_LogTraceM(
	    ioContext.getSystem().getLogger(),
	    "decimation", "Beagle::DecimateOp",
	    std::string("Applying decimation operation on the ")+
	    uint2ordinal(ioContext.getDemeIndex()+1)+" deme"
	);

	// Calculate the number of individuals to keep from the deme
	unsigned int lMu = 0;
	if(mDecimationRatio->getWrappedValue() == -1.0) {
		Beagle_AssertM(ioContext.getDemeIndex() < mPopSize->size());
		lMu = (*mPopSize)[ioContext.getDemeIndex()];
	} else {
		lMu = (unsigned int)std::ceil(mDecimationRatio->getWrappedValue()*float(ioDeme.size()));
		Beagle_AssertM(ioContext.getDemeIndex() < mPopSize->size());
		int lDiffSize = (*mPopSize)[ioContext.getDemeIndex()] - lMu;
		if((lDiffSize >= -1) && (lDiffSize <= 1)) lMu = (*mPopSize)[ioContext.getDemeIndex()];
	}
	Beagle_LogTraceM(
	    ioContext.getSystem().getLogger(),
	    "decimation", "Beagle::DecimateOp",
	    std::string("Keeping ")+uint2str(lMu)+" of the "+uint2str(ioDeme.size())+
	    " individuals from the "+uint2ordinal(ioContext.getDemeIndex()+1)+" deme"
	);

	// Check that the number of individuals to keep (mu) isn't greater than the deme size
	if(lMu > ioDeme.size()) {
		std::ostringstream lOSS;
		lOSS << "Warning: the actual population size (" << ioDeme.size();
		lOSS << ") is less than the desired decimation size (" << lMu;
		lOSS << "). Decimation is thus not applied.";
		Beagle_LogBasicM(
		    ioContext.getSystem().getLogger(),
		    "decimation", "Beagle::DecimateOp",
		    lOSS.str()
		);
		return;
	}

	// Copy the individuals to be kept into the deme
	std::make_heap(ioDeme.begin(), ioDeme.end(), IsLessPointerPredicate());
	Individual::Bag lSurvivors;
	for(unsigned int i=0; i<lMu; ++i) {
		lSurvivors.push_back(ioDeme.front());
		std::pop_heap(ioDeme.begin(), (ioDeme.end()-i), IsLessPointerPredicate());
	}
	ioDeme.clear();
	ioDeme.insert(ioDeme.begin(), lSurvivors.begin(), lSurvivors.end());
	Beagle_LogDetailedM(
	    ioContext.getSystem().getLogger(),
	    "decimation", "Beagle::DecimateOp",
	    std::string("There are now ")+uint2str(ioDeme.size())+" individuals in the "+
	    uint2ordinal(ioContext.getDemeIndex()+1)+" deme"
	);
	Beagle_StackTraceEndM("void DecimateOp::operate(Deme& ioDeme, Context& ioContext)");
}
/*!
 *  \brief Apply the oversize replacement strategy operation on a deme.
 *  \param ioDeme Reference to the deme on which the operation takes place.
 *  \param ioContext Evolutionary context of the operation.
 */
void OversizeOp::operate(Deme& ioDeme, Context& ioContext)
{
	Beagle_StackTraceBeginM();
	Beagle_NonNullPointerAssertM(getRootNode());
	Beagle_ValidateParameterM
	(mOversizeRatio->getWrappedValue() >= 1.0
	 || mOversizeRatio->getWrappedValue() == -1.0,
	 mOversizeRatioName,
	 "The oversize ratio must be greater than or equal to 1.0, or equal to -1.0.");
	
	Beagle_LogTraceM(
					 ioContext.getSystem().getLogger(),
					 "replacement-strategy", "Beagle::OversizeOp",
					 string("Using oversize replacement strategy to process the ")+
					 uint2ordinal(ioContext.getDemeIndex()+1)+" deme"
					 );
	Beagle_LogObjectM(
					  ioContext.getSystem().getLogger(),
					  Logger::eTrace,
					  "replacement-strategy", "Beagle::OversizeOp",
					  (*this)
					  );
	
	RouletteT<unsigned int> lRoulette;
	buildRoulette(lRoulette, ioContext);
	
	// Calculate the increase in size (lambda)
	float lRatio = mOversizeRatio->getWrappedValue();
	unsigned int lLambda;
	if (lRatio == -1.0) {
		// Using special ratio of -1.0 ensures deme grows to size specified in 'ec.pop.size'
		if (!ioContext.getSystem().getRegister().isRegistered("ec.pop.size")) {
			throw Beagle_RunTimeExceptionM(getName()+" requires register variable 'ec.pop.size'");
		}
		UIntArray::Handle lPopSize = castHandleT<UIntArray>
		(ioContext.getSystem().getRegister().getEntry("ec.pop.size"));
		unsigned int lSpecifiedDemeSize = (*lPopSize)[ioContext.getDemeIndex()];
		unsigned int lCurrentDemeSize = ioDeme.size();
		if (lSpecifiedDemeSize < lCurrentDemeSize) {
			throw Beagle_RunTimeExceptionM
			(std::string("For the ")+uint2ordinal(ioContext.getDemeIndex()+1)+
			 " deme, the size specified in 'ec.pop.size' ("+uint2str(lSpecifiedDemeSize)+
			 ") is less than the current deme size ("+uint2str(lCurrentDemeSize)+
			 ").  "+getName()+" can only increase the size of the deme.  Consider using DecimateOp "+
			 "if you wish to decrease the size of the deme");
		}
		lLambda = lSpecifiedDemeSize - lCurrentDemeSize;
	} else {
		// Using ratio to scale the deme's population
		lLambda = (unsigned int)ceil((lRatio-1.0)*float(ioDeme.size()));
	}
	Beagle_LogTraceM(
					 ioContext.getSystem().getLogger(),
					 "replacement-strategy", "Beagle::OversizeOp",
					 string("Population will be increased in size by ")+uint2str(lLambda)+" individuals"
					 );
	
	// Create the new individuals.
	Individual::Bag lOffsprings;
	for(unsigned int i=0; i<lLambda; ++i) {
		unsigned int lIndexBreeder = lRoulette.select(ioContext.getSystem().getRandomizer());
		BreederNode::Handle lSelectedBreeder=getRootNode();
		for(unsigned int j=0; j<lIndexBreeder; ++j)
			lSelectedBreeder=lSelectedBreeder->getNextSibling();
		Beagle_NonNullPointerAssertM(lSelectedBreeder);
		Beagle_NonNullPointerAssertM(lSelectedBreeder->getBreederOp());
		Individual::Handle lBredIndiv =
		lSelectedBreeder->getBreederOp()->breed(ioDeme, lSelectedBreeder->getFirstChild(), ioContext);
		Beagle_NonNullPointerAssertM(lBredIndiv);
		lOffsprings.push_back(lBredIndiv);
	}
	
	// Add the new individuals into the deme.
	ioDeme.insert(ioDeme.end(), lOffsprings.begin(), lOffsprings.end());
	Beagle_LogDetailedM(
						ioContext.getSystem().getLogger(),
						"replacement-strategy", "Beagle::OversizeOp",
						string("There are now ")+uint2str(ioDeme.size())+" individuals in the "+
						uint2ordinal(ioContext.getDemeIndex()+1)+" deme"
						);
	Beagle_StackTraceEndM("void OversizeOp::operate(Deme& ioDeme, Context& ioContext)");
}
/*!
 *  \brief Generate children from the breeder tree.
 *  \param ioDeme Deme to generate children from.
 *  \param ioContext Evolutionary context.
 *  \param lNbChildren Number of children to generate.
 *  \param inN Dimensionality of the problem.
 *  \param ioCMAValues CMA values to use to generate new individual.
 *  \param inSelectionWeights Selection weights used to generate children.
 */
void CMA::MuWCommaLambdaCMAFltVecOp::generateChildren(Deme& ioDeme,
        Context& ioContext,
        unsigned int inNbChildren,
        unsigned int inN,
        CMAValues& ioCMAValues,
        const Vector& inSelectionWeights) const
{
	Beagle_StackTraceBeginM();
	// Check parameters and log some information
	Beagle_NonNullPointerAssertM(mElitismKeepSize);
	Beagle_ValidateParameterM(mLMRatio->getWrappedValue() >= 1.0,
	                          mLMRatioName,
	                          "The LM ratio must be higher or equal to 1.0.");
	Beagle_ValidateParameterM(mElitismKeepSize->getWrappedValue() <= ioDeme.size(),
	                          "ec.elite.keepsize",
	                          "The elistism keepsize must be less than the deme size!");

	Beagle_LogTraceM(
	    ioContext.getSystem().getLogger(),
	    std::string("Using CMA-ES (mu_w,lambda) replacement strategy to process the ")+
	    uint2ordinal(ioContext.getDemeIndex()+1)+" deme"
	);
	Beagle_LogTraceM(ioContext.getSystem().getLogger(), (*this));
	const Factory& lFactory = ioContext.getSystem().getFactory();

	// Create weighted mean individual.
	std::sort(ioDeme.begin(), ioDeme.end(), IsMorePointerPredicate());

	Individual::Alloc::Handle lIndividualAlloc =
		castHandleT<Individual::Alloc>(lFactory.getConceptAllocator("Individual"));
	Individual::Handle lMeanInd = castHandleT<Individual>(lIndividualAlloc->allocate());
	Genotype::Alloc::Handle lGenotypeAlloc =
		castHandleT<Genotype::Alloc>(lFactory.getConceptAllocator("Genotype"));
	FltVec::FloatVector::Handle lMeanFloatVec =
		castHandleT<FltVec::FloatVector>(lGenotypeAlloc->allocate());
	lMeanFloatVec->resize(inN);
	lMeanInd->push_back(lMeanFloatVec);
	
	for(unsigned int i=0; i<inN; ++i) (*lMeanFloatVec)[i] = 0.0;
	if(ioDeme.size()==1) {
		Beagle_AssertM(ioDeme[0]->size() == 1);
		FltVec::FloatVector::Handle lInd = castHandleT<FltVec::FloatVector>((*ioDeme[0])[0]);
		(*lMeanFloatVec) = *lInd;
	} else {
		for(unsigned int i=0; i<ioDeme.size(); ++i) {
			Beagle_AssertM(ioDeme[i]->size()==1);
			FltVec::FloatVector::Handle lVecI = castHandleT<FltVec::FloatVector>((*ioDeme[i])[0]);
			Beagle_AssertM(lVecI->size()==inN);
			for(unsigned int j=0; j<inN; ++j) (*lMeanFloatVec)[j] += (inSelectionWeights[i] * (*lVecI)[j]);
		}
	}
	ioCMAValues.mXmean.resize(inN);
	for(unsigned int i=0; i<inN; ++i) ioCMAValues.mXmean[i] = (*lMeanFloatVec)[i];

	// Generate lambda children with breeder tree, first build breeder roulette
	RouletteT<unsigned int> lRoulette;
	buildRoulette(lRoulette, ioContext);

	// Keep best individuals if elitism is used
	const unsigned int lElitismKS=mElitismKeepSize->getWrappedValue();
	if(lElitismKS > 0) {
		Individual::Bag lBestInd;
		History::Handle lHistory = castHandleT<History>(ioContext.getSystem().haveComponent("History"));
		std::make_heap(ioDeme.begin(), ioDeme.end(), IsLessPointerPredicate());
		for(unsigned int i=0; i<lElitismKS; ++i) {
			if(lHistory != NULL) {
				HistoryID::Handle lHID = castHandleT<HistoryID>(ioDeme[0]->getMember("HistoryID"));
				std::vector<HistoryID> lParent;
				if(lHID != NULL) lParent.push_back(*lHID);
				lHistory->allocateNewID(*ioDeme[0]);
				lHistory->trace(ioContext, lParent, ioDeme[0], getName(), "elitism");
			}
			lBestInd.push_back(ioDeme[0]);
			std::pop_heap(ioDeme.begin(), ioDeme.end(), IsLessPointerPredicate());
			ioDeme.pop_back();
		}
		ioDeme.clear();
		ioDeme.insert(ioDeme.end(), lBestInd.begin(), lBestInd.end());
	} else ioDeme.clear();

	// Generate the children
	Individual::Bag lBagWithMeanInd;
	lBagWithMeanInd.push_back(lMeanInd);
	for(unsigned int i=0; i<inNbChildren; ++i) {
		unsigned int lIndexBreeder = lRoulette.select(ioContext.getSystem().getRandomizer());
		BreederNode::Handle lSelectedBreeder=getRootNode();
		for(unsigned int j=0; j<lIndexBreeder; ++j)
			lSelectedBreeder=lSelectedBreeder->getNextSibling();
		Beagle_NonNullPointerAssertM(lSelectedBreeder);
		Beagle_NonNullPointerAssertM(lSelectedBreeder->getBreederOp());
		Individual::Handle lBredIndiv =
		    lSelectedBreeder->getBreederOp()->breed(lBagWithMeanInd,
		                                            lSelectedBreeder->getFirstChild(),
		                                            ioContext);
		Beagle_NonNullPointerAssertM(lBredIndiv);
		ioDeme.push_back(lBredIndiv);
	}

	Beagle_StackTraceEndM();
}
Example #6
0
/*!
 *  \brief Apply NSGA2 multiobjective selection operator as a replacement strategy.
 *  \param ioDeme Deme on which selection operator is applied.
 *  \param ioContext Evolutionary context.
 */
void EMO::NSGA2Op::applyAsReplacementStrategy(Deme& ioDeme, Context& ioContext)
{
	Beagle_StackTraceBeginM();
	Beagle_LogTraceM(
	    ioContext.getSystem().getLogger(),
	    std::string("Processing using NSGA2 replacement strategy the ")+
	    uint2ordinal(ioContext.getDemeIndex()+1)+" deme"
	);
	Beagle_LogTraceM(ioContext.getSystem().getLogger(), (*this));

	// Generate a new generation of individuals, merged with the actual one.
	const unsigned int lLambda =
	    (unsigned int)std::ceil(mLMRatio->getWrappedValue()*float(ioDeme.size()));
	Beagle_LogVerboseM(
	    ioContext.getSystem().getLogger(),
	    "Generating " << lLambda << " offsprings using breeder tree"
	);
	RouletteT<unsigned int> lRoulette;
	buildRoulette(lRoulette, ioContext);
	Individual::Bag lOffsprings(ioDeme);
	for(unsigned int i=0; i<lLambda; ++i) {
		unsigned int lIndexBreeder = lRoulette.select(ioContext.getSystem().getRandomizer());
		BreederNode::Handle lSelectedBreeder=getRootNode();
		for(unsigned int j=0; j<lIndexBreeder; ++j)
			lSelectedBreeder=lSelectedBreeder->getNextSibling();
		Beagle_NonNullPointerAssertM(lSelectedBreeder);
		Beagle_NonNullPointerAssertM(lSelectedBreeder->getBreederOp());
		Individual::Handle lBredIndiv =
		    lSelectedBreeder->getBreederOp()->breed(ioDeme, lSelectedBreeder->getFirstChild(), ioContext);
		Beagle_NonNullPointerAssertM(lBredIndiv);
		lOffsprings.push_back(lBredIndiv);
	}

	// Fast non-dominated sorting, followed by insertion of the first Pareto fronts.
	Beagle_LogVerboseM(
	    ioContext.getSystem().getLogger(),
	    "Applying fast non-dominated sorting on the union of parents and offsprings individual"
	);
	NSGA2Op::Fronts lParetoFronts;
	sortFastND(lParetoFronts, ioDeme.size(), lOffsprings, ioContext);
	unsigned int lIndexDeme=0;
	for(unsigned int j=0; j<(lParetoFronts.size()-1); ++j) {
		for(unsigned int k=0; k<lParetoFronts[j].size(); ++k) {
			ioDeme[lIndexDeme++] = lOffsprings[lParetoFronts[j][k]];
		}
	}

	// Insertion of the last Pareto front, using crowding distance
	Individual::Bag lLastFrontIndiv;
	for(unsigned int l=0; l<lParetoFronts.back().size(); ++l) {
		lLastFrontIndiv.push_back(lOffsprings[lParetoFronts.back()[l]]);
	}
	NSGA2Op::Distances lDistances;
	Beagle_LogVerboseM(
	    ioContext.getSystem().getLogger(),
	    "Computing crowding distance on the " << uint2ordinal(lParetoFronts.size()) <<
	    " Pareto front, which is made of " << lParetoFronts.back().size() << " individuals"
	);
	evalCrowdingDistance(lDistances, lLastFrontIndiv);
	for(unsigned int m=0; lIndexDeme<ioDeme.size(); ++m) {
		ioDeme[lIndexDeme++] = lLastFrontIndiv[lDistances[m].second];
	}
	Beagle_StackTraceEndM();
}
Example #7
0
/*!
 *  \brief Apply NPGA2 multiobjective selection operator.
 *  \param ioDeme Deme on which selection operator is applied.
 *  \param ioContext Evolutionary context.
 */
void NPGA2Op::operate(Deme& ioDeme, Context& ioContext)
{
	Beagle_StackTraceBeginM();
	if(ioDeme.size() == 0) return;

	Beagle_LogTraceM(
	    ioContext.getSystem().getLogger(),
	    std::string("Applying NPGA2 multiobjective selection on the ")+
	    uint2ordinal(ioContext.getDemeIndex()+1)+" deme"
	);

	std::vector<bool> lAlreadySelectedIndiv(ioDeme.size(), false);
	Individual::Bag   lSelectedIndividual;
	const Factory&    lFactory = ioContext.getSystem().getFactory();

	// Generate new generation by selection
	for(unsigned int i=0; i<ioDeme.size(); ++i) {

		// First participant
		unsigned int lFirstParticipant =
		    ioContext.getSystem().getRandomizer().rollInteger(0, ioDeme.size()-1);
		std::vector<unsigned int> lNDParticipants(1, lFirstParticipant);

		// Following participants to tournament
		for(unsigned int j=1; j<mNumberParticipants->getWrappedValue(); ++j) {
			unsigned int lParticipant =
			    ioContext.getSystem().getRandomizer().rollInteger(0, ioDeme.size()-1);
			// Test if participant is dominated or dominate other participants
			bool lIsDominated = false;
			Fitness::Handle lPartFitness = ioDeme[lParticipant]->getFitness();
			for(unsigned int k=0; k<lNDParticipants.size(); ++k) {
				Fitness::Handle lFitnessNDk = ioDeme[lNDParticipants[k]]->getFitness();
				if(lPartFitness->isDominated(*lFitnessNDk)) {
					lIsDominated = true;
				} else if(lFitnessNDk->isDominated(*lPartFitness)) {
					lNDParticipants.erase(lNDParticipants.begin()+k);
				}
			}
			if(lIsDominated==false) lNDParticipants.push_back(lParticipant);
		}

		// Test if there is a tie. If so evaluate niche count.
		Beagle_AssertM(lNDParticipants.size() != 0);
		unsigned int lWinner = lNDParticipants[0];
		if(lNDParticipants.size() > 1) {
			float lLowestNicheCount = evalNicheCount(*ioDeme[lNDParticipants[0]], lSelectedIndividual);
			for(unsigned int j=1; j<lNDParticipants.size(); ++j) {
				float lNicheCount = evalNicheCount(*ioDeme[lNDParticipants[j]], lSelectedIndividual);
				if(lNicheCount < lLowestNicheCount) {
					lLowestNicheCount = lNicheCount;
					lWinner = lNDParticipants[j];
				}
			}
		}

		// Put winner in selected individual bag
		if(lAlreadySelectedIndiv[lWinner]) {
			std::string lIndividualType = ioDeme[lWinner]->getType();
			Individual::Alloc::Handle lIndividualAlloc =
				castHandleT<Individual::Alloc>(lFactory.getAllocator(lIndividualType));
			Individual::Handle lIndividual = castHandleT<Individual>(lIndividualAlloc->allocate());
			lIndividual->copy(*ioDeme[lWinner], ioContext.getSystem());
			lSelectedIndividual.push_back(lIndividual);
			Beagle_LogVerboseM(
			    ioContext.getSystem().getLogger(),
			    uint2ordinal(lWinner+1)+" individual selected again in NPGA2 selection process"
			);
		} else {
			lSelectedIndividual.push_back(ioDeme[lWinner]);
			lAlreadySelectedIndiv[lWinner] = true;
			Beagle_LogVerboseM(
			    ioContext.getSystem().getLogger(),
			    uint2ordinal(lWinner+1)+" individual selected in NPGA2 selection process"
			);
		}
	}

	// Copy selected individuals into deme
	for(unsigned int j=0; j<ioDeme.size(); ++j) ioDeme[j] = lSelectedIndividual[j];
	Beagle_StackTraceEndM();
}