RidgeKernelNormalizer.h

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00001 /*
00002  * This program is free software; you can redistribute it and/or modify
00003  * it under the terms of the GNU General Public License as published by
00004  * the Free Software Foundation; either version 3 of the License, or
00005  * (at your option) any later version.
00006  *
00007  * Written (W) 2009 Soeren Sonnenburg
00008  * Copyright (C) 2009 Fraunhofer Institute FIRST and Max-Planck-Society
00009  */
00010 
00011 #ifndef _RIDGEKERNELNORMALIZER_H___
00012 #define _RIDGEKERNELNORMALIZER_H___
00013 
00014 #include "kernel/KernelNormalizer.h"
00015 
00016 namespace shogun
00017 {
00043 class CRidgeKernelNormalizer : public CKernelNormalizer
00044 {
00045     public:
00056         CRidgeKernelNormalizer(float64_t r=1e-10, float64_t c=0.0)
00057         {
00058             scale=c;
00059             ridge=r;
00060         }
00061 
00063         virtual ~CRidgeKernelNormalizer()
00064         {
00065         }
00066 
00069         virtual bool init(CKernel* k)
00070         {
00071             if (scale<=0)
00072             {
00073                 ASSERT(k);
00074                 int32_t num=k->get_num_vec_lhs();
00075                 ASSERT(num>0);
00076 
00077                 CFeatures* old_lhs=k->lhs;
00078                 CFeatures* old_rhs=k->rhs;
00079                 k->lhs=old_lhs;
00080                 k->rhs=old_lhs;
00081 
00082                 float64_t sum=0;
00083                 for (int32_t i=0; i<num; i++)
00084                     sum+=k->compute(i, i);
00085 
00086                 scale=sum/num;
00087                 k->lhs=old_lhs;
00088                 k->rhs=old_rhs;
00089             }
00090 
00091             ridge*=scale;
00092             return true;
00093         }
00094 
00100         inline virtual float64_t normalize(
00101             float64_t value, int32_t idx_lhs, int32_t idx_rhs)
00102         {
00103             if (idx_lhs==idx_rhs)
00104                 return value+ridge;
00105             else
00106                 return value;
00107         }
00108 
00113         inline virtual float64_t normalize_lhs(float64_t value, int32_t idx_lhs)
00114         {
00115             SG_ERROR("linadd not supported with Ridge normalization.\n");
00116             return 0;
00117         }
00118 
00123         inline virtual float64_t normalize_rhs(float64_t value, int32_t idx_rhs)
00124         {
00125             SG_ERROR("linadd not supported with Ridge normalization.\n");
00126             return 0;
00127         }
00128 
00130         inline virtual const char* get_name() const { return "RidgeKernelNormalizer"; }
00131 
00132     protected:
00134         float64_t ridge;
00136         float64_t scale;
00137 };
00138 }
00139 #endif // _RIDGEKERNELNORMALIZER_H___
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