CRNSpectralClustering.h

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/* Copyright 2012-2014 INSA Lyon, CoReNum
 * 
 * This file is part of libcrn.
 * 
 * libcrn 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.
 * 
 * libcrn 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 libcrn.  If not, see <http://www.gnu.org/licenses/>.
 * 
 * file: CRNSpectralClustering.h
 * \author Yann LEYDIER
 */

#ifndef CRNSpectralClustering_HEADER
#define CRNSpectralClustering_HEADER

#include <CRN.h>
#include <CRNMath/CRNMatrixDoublePtr.h>
#include <vector>
#include <map>
#include <limits>

namespace crn
{
    class SpectralClustering;
    CRN_ALIAS_SMART_PTR(SpectralClustering)
}
namespace crn
{
    class SquareMatrixDouble;
    /****************************************************************************/
    class SpectralClustering
    {
        public:
            SpectralClustering(const SpectralClustering&) = delete;
            SpectralClustering(SpectralClustering&&) = default;
            SpectralClustering& operator=(const SpectralClustering&) = delete;
            SpectralClustering& operator=(SpectralClustering&&) = default;

            static SpectralClustering CreateLocalScaleFromNN(const SquareMatrixDouble &distance_matrix, size_t sigma_neighborhood = 7, double epsilon = std::numeric_limits<double>::max());
            static SpectralClustering CreateGlobalScaleFromDimension(const SquareMatrixDouble &distance_matrix, size_t dimension, double epsilon = std::numeric_limits<double>::max());
            static SpectralClustering CreateGlobalScaleFromNN(const SquareMatrixDouble &distance_matrix, size_t sigma_neighborhood = 1, double epsilon = std::numeric_limits<double>::max());
            static SpectralClustering CreateFixedScale(const SquareMatrixDouble &distance_matrix, double sigma, double epsilon = std::numeric_limits<double>::max());
            
            const std::multimap<double, MatrixDouble>& GetEigenpairs() const noexcept { return eigenpairs; }
            std::vector<double> GetEigenvalues() const;
            size_t EstimateClusterNumber(double limit = 1.0) const;
            std::vector<std::vector<double>> ProjectData(size_t ncoordinates, bool normalize) const;

        private:
            SpectralClustering(const SquareMatrixDouble &w);

            std::multimap<double, MatrixDouble> eigenpairs; 
    };
}

#endif