SHOGUN
v1.1.0
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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/kernel/Chi2Kernel.h> 00013 #include <shogun/features/Features.h> 00014 #include <shogun/features/SimpleFeatures.h> 00015 #include <shogun/io/SGIO.h> 00016 00017 using namespace shogun; 00018 00019 void 00020 CChi2Kernel::init() 00021 { 00022 m_parameters->add(&width, "width"); 00023 } 00024 00025 CChi2Kernel::CChi2Kernel() 00026 : CDotKernel(0), width(0) 00027 { 00028 init(); 00029 } 00030 00031 CChi2Kernel::CChi2Kernel(int32_t size, float64_t w) 00032 : CDotKernel(size), width(w) 00033 { 00034 init(); 00035 } 00036 00037 CChi2Kernel::CChi2Kernel( 00038 CSimpleFeatures<float64_t>* l, CSimpleFeatures<float64_t>* r, float64_t w, int32_t size) 00039 : CDotKernel(size), width(w) 00040 { 00041 init(); 00042 init(l,r); 00043 } 00044 00045 CChi2Kernel::~CChi2Kernel() 00046 { 00047 cleanup(); 00048 } 00049 00050 bool CChi2Kernel::init(CFeatures* l, CFeatures* r) 00051 { 00052 bool result=CDotKernel::init(l,r); 00053 init_normalizer(); 00054 return result; 00055 } 00056 00057 float64_t CChi2Kernel::compute(int32_t idx_a, int32_t idx_b) 00058 { 00059 int32_t alen, blen; 00060 bool afree, bfree; 00061 00062 float64_t* avec= 00063 ((CSimpleFeatures<float64_t>*) lhs)->get_feature_vector(idx_a, alen, afree); 00064 float64_t* bvec= 00065 ((CSimpleFeatures<float64_t>*) rhs)->get_feature_vector(idx_b, blen, bfree); 00066 ASSERT(alen==blen); 00067 00068 float64_t result=0; 00069 for (int32_t i=0; i<alen; i++) 00070 { 00071 float64_t n=avec[i]-bvec[i]; 00072 float64_t d=avec[i]+bvec[i]; 00073 if (d!=0) 00074 result+=n*n/d; 00075 } 00076 00077 result=exp(-result/width); 00078 00079 ((CSimpleFeatures<float64_t>*) lhs)->free_feature_vector(avec, idx_a, afree); 00080 ((CSimpleFeatures<float64_t>*) rhs)->free_feature_vector(bvec, idx_b, bfree); 00081 00082 return result; 00083 }