/usr/include/shogun/kernel/FirstElementKernelNormalizer.h is in libshogun-dev 1.1.0-4ubuntu2.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 | /*
* 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) 2008-2009 Soeren Sonnenburg
* Copyright (C) 2008-2009 Fraunhofer Institute FIRST and Max-Planck-Society
*/
#ifndef _FIRSTELEMENTKERNELNORMALIZER_H___
#define _FIRSTELEMENTKERNELNORMALIZER_H___
#include <shogun/kernel/KernelNormalizer.h>
namespace shogun
{
/** @brief Normalize the kernel by a constant obtained from the first element of the
* kernel matrix, i.e. \f$ c=k({\bf x},{\bf x})\f$
*
* \f[
* k'(x,x')= \frac{k(x,x')}{c}
* \f]
*
* useful if the kernel returns constant elements along the diagonal anyway and
* all one wants is to scale the kernel down to 1 on the diagonal.
*/
class CFirstElementKernelNormalizer : public CKernelNormalizer
{
public:
/** constructor
*/
CFirstElementKernelNormalizer() : CKernelNormalizer(), scale(1.0)
{
m_parameters->add(&scale, "scale",
"Scale quotient by which kernel is scaled.");
}
/** default destructor */
virtual ~CFirstElementKernelNormalizer()
{
}
/** initialization of the normalizer (if needed)
* @param k kernel */
virtual bool init(CKernel* k)
{
CFeatures* old_lhs=k->lhs;
CFeatures* old_rhs=k->rhs;
k->lhs=old_lhs;
k->rhs=old_lhs;
scale=k->compute(0, 0);
k->lhs=old_lhs;
k->rhs=old_rhs;
return true;
}
/** normalize the kernel value
* @param value kernel value
* @param idx_lhs index of left hand side vector
* @param idx_rhs index of right hand side vector
*/
inline virtual float64_t normalize(
float64_t value, int32_t idx_lhs, int32_t idx_rhs)
{
return value/scale;
}
/** normalize only the left hand side vector
* @param value value of a component of the left hand side feature vector
* @param idx_lhs index of left hand side vector
*/
inline virtual float64_t normalize_lhs(float64_t value, int32_t idx_lhs)
{
return value/sqrt(scale);
}
/** normalize only the right hand side vector
* @param value value of a component of the right hand side feature vector
* @param idx_rhs index of right hand side vector
*/
inline virtual float64_t normalize_rhs(float64_t value, int32_t idx_rhs)
{
return value/sqrt(scale);
}
/** @return object name */
inline virtual const char* get_name() const { return "FirstElementKernelNormalizer"; }
protected:
/// scale constant obtained from k(0,0)
float64_t scale;
};
}
#endif
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