SHOGUN v0.9.0
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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) 1999-2009 Soeren Sonnenburg 00008 * Copyright (C) 1999-2009 Fraunhofer Institute FIRST and Max-Planck-Society 00009 */ 00010 00011 #include "lib/common.h" 00012 #include "lib/io.h" 00013 #include "kernel/GaussianMatchStringKernel.h" 00014 #include "kernel/SqrtDiagKernelNormalizer.h" 00015 #include "features/Features.h" 00016 #include "features/StringFeatures.h" 00017 00018 using namespace shogun; 00019 00020 CGaussianMatchStringKernel::CGaussianMatchStringKernel(void) 00021 : CStringKernel<char>(0), width(0.0) 00022 { 00023 SG_UNSTABLE("CGaussianMatchStringKernel::" 00024 "CGaussianMatchStringKernel(void)", "\n"); 00025 00026 set_normalizer(new CSqrtDiagKernelNormalizer()); 00027 } 00028 00029 CGaussianMatchStringKernel::CGaussianMatchStringKernel(int32_t size, float64_t w) 00030 : CStringKernel<char>(size), width(w) 00031 { 00032 set_normalizer(new CSqrtDiagKernelNormalizer()); 00033 } 00034 00035 CGaussianMatchStringKernel::CGaussianMatchStringKernel( 00036 CStringFeatures<char>* l, CStringFeatures<char>* r, float64_t w) 00037 : CStringKernel<char>(10), width(w) 00038 { 00039 set_normalizer(new CSqrtDiagKernelNormalizer()); 00040 init(l, r); 00041 } 00042 00043 CGaussianMatchStringKernel::~CGaussianMatchStringKernel() 00044 { 00045 cleanup(); 00046 } 00047 00048 bool CGaussianMatchStringKernel::init(CFeatures* l, CFeatures* r) 00049 { 00050 CStringKernel<char>::init(l, r); 00051 return init_normalizer(); 00052 } 00053 00054 void CGaussianMatchStringKernel::cleanup() 00055 { 00056 CKernel::cleanup(); 00057 } 00058 00059 float64_t CGaussianMatchStringKernel::compute(int32_t idx_a, int32_t idx_b) 00060 { 00061 int32_t i, alen, blen ; 00062 bool free_avec, free_bvec; 00063 00064 char* avec = ((CStringFeatures<char>*) lhs)->get_feature_vector(idx_a, alen, free_avec); 00065 char* bvec = ((CStringFeatures<char>*) rhs)->get_feature_vector(idx_b, blen, free_bvec); 00066 00067 float64_t result=0; 00068 00069 ASSERT(alen==blen); 00070 00071 for (i = 0; i<alen; i++) 00072 result+=(avec[i]==bvec[i]) ? 0:4; 00073 00074 result=exp(-result/width); 00075 00076 00077 ((CStringFeatures<char>*) lhs)->free_feature_vector(avec, idx_a, free_avec); 00078 ((CStringFeatures<char>*) rhs)->free_feature_vector(bvec, idx_b, free_bvec); 00079 return result; 00080 }