SparseEuclideanDistance.cpp

浏览该文件的文档.

/*
 * 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) 2007-2009 Soeren Sonnenburg
 * Copyright (C) 2007-2009 Fraunhofer Institute FIRST and Max-Planck-Society
 */

#include <shogun/lib/common.h>
#include <shogun/io/SGIO.h>
#include <shogun/distance/SparseEuclideanDistance.h>
#include <shogun/features/Features.h>
#include <shogun/features/SparseFeatures.h>

using namespace shogun;

CSparseEuclideanDistance::CSparseEuclideanDistance()
: CSparseDistance<float64_t>()
{
    init();
}

CSparseEuclideanDistance::CSparseEuclideanDistance(
    CSparseFeatures<float64_t>* l, CSparseFeatures<float64_t>* r)
: CSparseDistance<float64_t>()
{
    init();
    init(l, r);
}

CSparseEuclideanDistance::~CSparseEuclideanDistance()
{
    cleanup();
}

bool CSparseEuclideanDistance::init(CFeatures* l, CFeatures* r)
{
    CSparseDistance<float64_t>::init(l, r);

    cleanup();

    sq_lhs=SG_MALLOC(float64_t, lhs->get_num_vectors());
    sq_lhs=((CSparseFeatures<float64_t>*) lhs)->compute_squared(sq_lhs);

    if (lhs==rhs)
        sq_rhs=sq_lhs;
    else
    {
        sq_rhs=SG_MALLOC(float64_t, rhs->get_num_vectors());
        sq_rhs=((CSparseFeatures<float64_t>*) rhs)->compute_squared(sq_rhs);
    }

    return true;
}

void CSparseEuclideanDistance::cleanup()
{
    if (sq_lhs != sq_rhs)
        SG_FREE(sq_rhs);
    sq_rhs = NULL;

    SG_FREE(sq_lhs);
    sq_lhs = NULL;
}

float64_t CSparseEuclideanDistance::compute(int32_t idx_a, int32_t idx_b)
{
    float64_t result=((CSparseFeatures<float64_t>*) lhs)->compute_squared_norm(
        (CSparseFeatures<float64_t>*) lhs, sq_lhs, idx_a,
        (CSparseFeatures<float64_t>*) rhs, sq_rhs, idx_b);

    return CMath::sqrt(result);
}

void CSparseEuclideanDistance::init()
{
    sq_lhs=NULL;
    sq_rhs=NULL;
}