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

#ifndef _AVGDIAGKERNELNORMALIZER_H___
#define _AVGDIAGKERNELNORMALIZER_H___

#include <shogun/kernel/normalizer/KernelNormalizer.h>
namespace shogun
{
class CAvgDiagKernelNormalizer : public CKernelNormalizer
{
    public:
        CAvgDiagKernelNormalizer(float64_t c=0.0) : CKernelNormalizer()
        {
            scale=c;

            SG_ADD(&scale, "scale", "Scale quotient by which kernel is scaled.",
                MS_AVAILABLE);
        }

        virtual ~CAvgDiagKernelNormalizer()
        {
        }

        virtual bool init(CKernel* k)
        {
            if (scale<=0)
            {
                ASSERT(k);
                int32_t num=k->get_num_vec_lhs();
                ASSERT(num>0);

                CFeatures* old_lhs=k->lhs;
                CFeatures* old_rhs=k->rhs;
                k->lhs=old_lhs;
                k->rhs=old_lhs;

                float64_t sum=0;
                for (int32_t i=0; i<num; i++)
                    sum+=k->compute(i, i);

                scale=sum/num;
                k->lhs=old_lhs;
                k->rhs=old_rhs;
            }

            return true;
        }

        virtual float64_t normalize(
            float64_t value, int32_t idx_lhs, int32_t idx_rhs)
        {
            return value/scale;
        }

        virtual float64_t normalize_lhs(float64_t value, int32_t idx_lhs)
        {
            return value/sqrt(scale);
        }

        virtual float64_t normalize_rhs(float64_t value, int32_t idx_rhs)
        {
            return value/sqrt(scale);
        }

        virtual const char* get_name() const { return "AvgDiagKernelNormalizer"; }

    protected:
        float64_t scale;
};
}
#endif