UniformRanking.h

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/*!
 *
 *
 * \brief       Roulette-Wheel-Selection using uniform selection probability assignment.
 *
 *
 *
 * \author      T.Voss
 * \date        2010-2011
 *
 *
 * \par Copyright 1995-2017 Shark Development Team
 *
 * <BR><HR>
 * This file is part of Shark.
 * <http://shark-ml.org/>
 *
 * Shark 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 3 of the License, or
 * (at your option) any later version.
 *
 * Shark 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 Shark.  If not, see <http://www.gnu.org/licenses/>.
 *
 */
#ifndef SHARK_ALGORITHMS_DIRECTSEARCH_OPERATORS_SELECTION_UNIFORMRANKING_H
#define SHARK_ALGORITHMS_DIRECTSEARCH_OPERATORS_SELECTION_UNIFORMRANKING_H

#include <shark/Algorithms/DirectSearch/Operators/Selection/RouletteWheelSelection.h>

namespace shark {
/// \brief Selects individuals from the range of individual and offspring individuals.
struct UniformRankingSelection {

    /// \brief Selects individuals from the range of individual and offspring individuals.
    ///
    /// The operator carries out the following steps:
    ///   - Assign uniform selection probabilities to all individuals.
    ///   - Carry out roulette wheel selection on the range of individual and 
    ///     offspring individuals until the output range is filled.
    ///
    /// \param [in] individuals Iterator pointing to the first valid individual.
    /// \param [in] individualsE Iterator pointing to the first invalid individual.
    /// \param [in] out Iterator pointing to the first valid element of the output range.
    /// \param [in] outE Iterator pointing to the first invalid element of the output range.
    template<typename RngType, typename InIterator,typename OutIterator> 
    void operator()( 
        RngType& rng,
        InIterator individuals,
        InIterator individualsE,
        OutIterator out,
        OutIterator outE
    ){
        std::size_t size = std::distance( individuals, individualsE );
        
        RealVector selectionProbability(size,1.0/size);
        RouletteWheelSelection rws;
        for( ; out != outE; ++out ){
            *out = *rws(rng, individuals, individualsE, selectionProbability);
        }
    }

};

}

#endif