MultidimensionalScaling.cpp

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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) 2011-2013 Sergey Lisitsyn
 * Copyright (C) 2011-2013 Berlin Institute of Technology and Max-Planck-Society
 */

#include <shogun/converter/MultidimensionalScaling.h>
#include <shogun/converter/EmbeddingConverter.h>
#include <shogun/mathematics/lapack.h>
#include <shogun/distance/CustomDistance.h>
#include <shogun/lib/common.h>
#include <shogun/mathematics/Math.h>
#include <shogun/mathematics/Statistics.h>
#include <shogun/io/SGIO.h>
#include <shogun/distance/EuclideanDistance.h>
#include <shogun/lib/tapkee/tapkee_shogun.hpp>

using namespace shogun;

CMultidimensionalScaling::CMultidimensionalScaling() : CEmbeddingConverter()
{
    m_eigenvalues = SGVector<float64_t>();
    m_landmark_number = 3;
    m_landmark = false;

    init();
}

void CMultidimensionalScaling::init()
{
    SG_ADD(&m_eigenvalues, "eigenvalues", "eigenvalues of last embedding",
        MS_NOT_AVAILABLE);
    SG_ADD(&m_landmark, "landmark",
        "indicates if landmark approximation should be used", MS_NOT_AVAILABLE);
    SG_ADD(&m_landmark_number, "landmark_number",
        "the number of landmarks for approximation", MS_AVAILABLE);
}

CMultidimensionalScaling::~CMultidimensionalScaling()
{
}

SGVector<float64_t> CMultidimensionalScaling::get_eigenvalues() const
{
    return m_eigenvalues;
}

void CMultidimensionalScaling::set_landmark_number(int32_t num)
{
    if (num<3)
        SG_ERROR("Number of landmarks should be greater than 3 to make triangulation possible while %d given.",
                 num);
    m_landmark_number = num;
}

int32_t CMultidimensionalScaling::get_landmark_number() const
{
    return m_landmark_number;
}

void CMultidimensionalScaling::set_landmark(bool landmark)
{
    m_landmark = landmark;
}

bool CMultidimensionalScaling::get_landmark() const
{
    return m_landmark;
}

const char* CMultidimensionalScaling::get_name() const
{
    return "MultidimensionalScaling";
};

CDenseFeatures<float64_t>* CMultidimensionalScaling::embed_distance(CDistance* distance)
{
    TAPKEE_PARAMETERS_FOR_SHOGUN parameters;
    if (m_landmark)
    {
        parameters.method = SHOGUN_LANDMARK_MULTIDIMENSIONAL_SCALING;
        parameters.landmark_ratio = float64_t(m_landmark_number)/distance->get_num_vec_lhs();
        if (parameters.landmark_ratio > 1.0) {
            SG_WARNING("Number of landmarks (%d) exceeds number of feature vectors (%d)",m_landmark_number,distance->get_num_vec_lhs());
            parameters.landmark_ratio = 1.0;
        }
    }
    else
    {
        parameters.method = SHOGUN_MULTIDIMENSIONAL_SCALING;
    }
    parameters.target_dimension = m_target_dim;
    parameters.distance = distance;
    CDenseFeatures<float64_t>* embedding = tapkee_embed(parameters);
    return embedding;
}

CFeatures* CMultidimensionalScaling::apply(CFeatures* features)
{
    SG_REF(features);
    ASSERT(m_distance)

    m_distance->init(features,features);
    CDenseFeatures<float64_t>* embedding = embed_distance(m_distance);
    m_distance->remove_lhs_and_rhs();

    SG_UNREF(features);
    return (CFeatures*)embedding;
}