SHOGUN
v3.2.0
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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 <shogun/lib/common.h> 00012 #include <shogun/io/SGIO.h> 00013 #include <shogun/kernel/string/GaussianMatchStringKernel.h> 00014 #include <shogun/kernel/normalizer/SqrtDiagKernelNormalizer.h> 00015 #include <shogun/features/Features.h> 00016 #include <shogun/features/StringFeatures.h> 00017 00018 using namespace shogun; 00019 00020 CGaussianMatchStringKernel::CGaussianMatchStringKernel() 00021 : CStringKernel<char>(0), width(0.0) 00022 { 00023 set_normalizer(new CSqrtDiagKernelNormalizer()); 00024 register_params(); 00025 } 00026 00027 CGaussianMatchStringKernel::CGaussianMatchStringKernel(int32_t size, float64_t w) 00028 : CStringKernel<char>(size), width(w) 00029 { 00030 set_normalizer(new CSqrtDiagKernelNormalizer()); 00031 register_params(); 00032 } 00033 00034 CGaussianMatchStringKernel::CGaussianMatchStringKernel( 00035 CStringFeatures<char>* l, CStringFeatures<char>* r, float64_t w) 00036 : CStringKernel<char>(10), width(w) 00037 { 00038 set_normalizer(new CSqrtDiagKernelNormalizer()); 00039 init(l, r); 00040 register_params(); 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 } 00081 00082 void CGaussianMatchStringKernel::register_params() 00083 { 00084 SG_ADD(&width, "width", "kernel width", MS_AVAILABLE); 00085 }