SHOGUN
v2.0.0
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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) 2008-2009 Christian Gehl 00008 * Copyright (C) 2008-2009 Fraunhofer Institute FIRST 00009 */ 00010 00011 #include <shogun/lib/config.h> 00012 #include <shogun/lib/common.h> 00013 #include <shogun/io/SGIO.h> 00014 #include <shogun/distance/CosineDistance.h> 00015 #include <shogun/features/Features.h> 00016 00017 using namespace shogun; 00018 00019 CCosineDistance::CCosineDistance() 00020 : CDenseDistance<float64_t>() 00021 { 00022 } 00023 00024 CCosineDistance::CCosineDistance(CDenseFeatures<float64_t>* l, CDenseFeatures<float64_t>* r) 00025 : CDenseDistance<float64_t>() 00026 { 00027 init(l, r); 00028 } 00029 00030 CCosineDistance::~CCosineDistance() 00031 { 00032 cleanup(); 00033 } 00034 00035 bool CCosineDistance::init(CFeatures* l, CFeatures* r) 00036 { 00037 return CDenseDistance<float64_t>::init(l,r); 00038 } 00039 00040 void CCosineDistance::cleanup() 00041 { 00042 } 00043 00044 float64_t CCosineDistance::compute(int32_t idx_a, int32_t idx_b) 00045 { 00046 int32_t alen, blen; 00047 bool afree, bfree; 00048 00049 float64_t* avec= 00050 ((CDenseFeatures<float64_t>*) lhs)->get_feature_vector(idx_a, alen, afree); 00051 float64_t* bvec= 00052 ((CDenseFeatures<float64_t>*) rhs)->get_feature_vector(idx_b, blen, bfree); 00053 00054 ASSERT(alen==blen); 00055 float64_t s=0; 00056 float64_t ab=0; 00057 float64_t sa=0; 00058 float64_t sb=0; 00059 { 00060 for (int32_t i=0; i<alen; i++) 00061 { 00062 ab+=avec[i]*bvec[i]; 00063 sa+=pow(fabs(avec[i]),2); 00064 sb+=pow(fabs(bvec[i]),2); 00065 } 00066 } 00067 00068 ((CDenseFeatures<float64_t>*) lhs)->free_feature_vector(avec, idx_a, afree); 00069 ((CDenseFeatures<float64_t>*) rhs)->free_feature_vector(bvec, idx_b, bfree); 00070 00071 s=sqrt(sa)*sqrt(sb); 00072 00073 // trap division by zero 00074 if(s==0) 00075 return 0; 00076 00077 s=1-ab/s; 00078 if(s<0) 00079 return 0; 00080 else 00081 return s ; 00082 }