LMNNImpl.h

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/*
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * Written (W) 2013 Fernando J. Iglesias Garcia
 * Copyright (C) 2013 Fernando J. Iglesias Garcia
 */

#ifndef LMNNIMPL_H_
#define LMNNIMPL_H_

#include <shogun/lib/config.h>

#ifdef HAVE_EIGEN3

#include <shogun/lib/common.h>
#include <shogun/lib/SGMatrix.h>
#include <shogun/features/DenseFeatures.h>
#include <shogun/labels/MulticlassLabels.h>
#include <shogun/distance/EuclideanDistance.h>
#include <Eigen/Dense>

#include <set>
#include <vector>

#ifndef DOXYGEN_SHOULD_SKIP_THIS

namespace shogun
{

struct CImpostorNode;

typedef std::set<CImpostorNode> ImpostorsSetType;

struct CImpostorNode
{
    CImpostorNode(index_t ex, index_t tar, index_t imp);

    bool operator<(const CImpostorNode& rhs) const;

    index_t example;

    index_t target;

    index_t impostor;
};

class CLMNNImpl
{
    public:

        static void check_training_setup(CFeatures* features, const CLabels* labels, SGMatrix<float64_t>& init_transform);

        static SGMatrix<index_t> find_target_nn(CDenseFeatures<float64_t>* x, CMulticlassLabels* y, int32_t k);

        static Eigen::MatrixXd sum_outer_products(CDenseFeatures<float64_t>* x, const SGMatrix<index_t> target_nn);

        static ImpostorsSetType find_impostors(CDenseFeatures<float64_t>* x, CMulticlassLabels* y, const Eigen::MatrixXd& L, const SGMatrix<index_t> target_nn, const uint32_t iter, const uint32_t correction);

        static void update_gradient(CDenseFeatures<float64_t>* x, Eigen::MatrixXd& G, const ImpostorsSetType& Nc, const ImpostorsSetType& Np, float64_t mu);

        static void gradient_step(Eigen::MatrixXd& L, const Eigen::MatrixXd& G, float64_t stepsize, bool diagonal);

        static void correct_stepsize(float64_t& stepsize, const SGVector<float64_t> obj, const uint32_t iter);

        static bool check_termination(float64_t stepsize, const SGVector<float64_t> obj, uint32_t iter, uint32_t maxiter, float64_t stepsize_threshold, float64_t obj_threshold);

    private:

        static SGMatrix<float64_t> compute_pca_transform(CDenseFeatures<float64_t>* features);

        static Eigen::MatrixXd compute_sqdists(Eigen::MatrixXd& L, const SGMatrix<index_t> target_nn);

        static SGVector<float64_t> compute_impostors_sqdists(Eigen::MatrixXd& L, const ImpostorsSetType& Nexact);

        static ImpostorsSetType find_impostors_exact(Eigen::MatrixXd& LX, const Eigen::MatrixXd& sqdists, CMulticlassLabels* y, const SGMatrix<index_t> target_nn, int32_t k);

        static ImpostorsSetType find_impostors_approx(Eigen::MatrixXd& LX, const Eigen::MatrixXd& sqdists, const ImpostorsSetType& Nexact, const SGMatrix<index_t> target_nn);

        static std::vector<index_t> get_examples_label(CMulticlassLabels* y, float64_t yi);

        static std::vector<index_t> get_examples_gtlabel(CMulticlassLabels* y, float64_t yi);

        static CEuclideanDistance* setup_distance(CDenseFeatures<float64_t>* x, std::vector<index_t>& a, std::vector<index_t>& b);


}; /* class CLMNNImpl */

} /* namespace shogun */

#endif /* DOXYGEN_SHOULD_SKIP_THIS */

#endif /* HAVE_EIGEN3 */

#endif /* _LMNNIMPL_H_ */