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) 2006-2009 Christian Gehl 00008 * Copyright (C) 2006-2009 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/GeodesicMetric.h> 00015 #include <shogun/features/Features.h> 00016 00017 using namespace shogun; 00018 00019 CGeodesicMetric::CGeodesicMetric() : CDenseDistance<float64_t>() 00020 { 00021 } 00022 00023 CGeodesicMetric::CGeodesicMetric(CDenseFeatures<float64_t>* l, CDenseFeatures<float64_t>* r) 00024 : CDenseDistance<float64_t>() 00025 { 00026 init(l, r); 00027 } 00028 00029 CGeodesicMetric::~CGeodesicMetric() 00030 { 00031 cleanup(); 00032 } 00033 00034 bool CGeodesicMetric::init(CFeatures* l, CFeatures* r) 00035 { 00036 bool result=CDenseDistance<float64_t>::init(l,r); 00037 00038 return result; 00039 } 00040 00041 void CGeodesicMetric::cleanup() 00042 { 00043 } 00044 00045 float64_t CGeodesicMetric::compute(int32_t idx_a, int32_t idx_b) 00046 { 00047 int32_t alen, blen; 00048 bool afree, bfree; 00049 00050 float64_t* avec= 00051 ((CDenseFeatures<float64_t>*) lhs)->get_feature_vector(idx_a, alen, afree); 00052 float64_t* bvec= 00053 ((CDenseFeatures<float64_t>*) rhs)->get_feature_vector(idx_b, blen, bfree); 00054 00055 ASSERT(alen==blen); 00056 00057 float64_t s=0; 00058 float64_t d=0; 00059 float64_t nx=0; 00060 float64_t ny=0; 00061 { 00062 for (int32_t i=0; i<alen; i++) 00063 { 00064 d+=avec[i]*bvec[i]; 00065 nx+=avec[i]*avec[i]; 00066 ny+=bvec[i]*bvec[i]; 00067 s+=avec[i]+bvec[i]; 00068 } 00069 } 00070 00071 ((CDenseFeatures<float64_t>*) lhs)->free_feature_vector(avec, idx_a, afree); 00072 ((CDenseFeatures<float64_t>*) rhs)->free_feature_vector(bvec, idx_b, bfree); 00073 00074 00075 // trap division by zero 00076 if(s==0 || nx==0 || ny==0) 00077 return 0; 00078 00079 d/=CMath::sqrt(nx*ny); 00080 00081 // can only happen due to numerical problems 00082 if (CMath::abs(d)>1.0) 00083 d=CMath::sign(d); 00084 00085 return acos(d); 00086 }