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) 2006-2009 Christian Gehl 00008 * Copyright (C) 2006-2009 Fraunhofer Institute FIRST 00009 */ 00010 00011 #include "lib/config.h" 00012 #include "lib/common.h" 00013 #include "lib/io.h" 00014 #include "distance/GeodesicMetric.h" 00015 #include "features/Features.h" 00016 #include "features/SimpleFeatures.h" 00017 00018 using namespace shogun; 00019 00020 CGeodesicMetric::CGeodesicMetric() : CSimpleDistance<float64_t>() 00021 { 00022 } 00023 00024 CGeodesicMetric::CGeodesicMetric(CSimpleFeatures<float64_t>* l, CSimpleFeatures<float64_t>* r) 00025 : CSimpleDistance<float64_t>() 00026 { 00027 init(l, r); 00028 } 00029 00030 CGeodesicMetric::~CGeodesicMetric() 00031 { 00032 cleanup(); 00033 } 00034 00035 bool CGeodesicMetric::init(CFeatures* l, CFeatures* r) 00036 { 00037 bool result=CSimpleDistance<float64_t>::init(l,r); 00038 00039 return result; 00040 } 00041 00042 void CGeodesicMetric::cleanup() 00043 { 00044 } 00045 00046 float64_t CGeodesicMetric::compute(int32_t idx_a, int32_t idx_b) 00047 { 00048 int32_t alen, blen; 00049 bool afree, bfree; 00050 00051 float64_t* avec= 00052 ((CSimpleFeatures<float64_t>*) lhs)->get_feature_vector(idx_a, alen, afree); 00053 float64_t* bvec= 00054 ((CSimpleFeatures<float64_t>*) rhs)->get_feature_vector(idx_b, blen, bfree); 00055 00056 ASSERT(alen==blen); 00057 00058 float64_t s=0; 00059 float64_t d=0; 00060 float64_t nx=0; 00061 float64_t ny=0; 00062 { 00063 for (int32_t i=0; i<alen; i++) 00064 { 00065 d+=avec[i]*bvec[i]; 00066 nx+=avec[i]*avec[i]; 00067 ny+=bvec[i]*bvec[i]; 00068 s+=avec[i]+bvec[i]; 00069 } 00070 } 00071 00072 ((CSimpleFeatures<float64_t>*) lhs)->free_feature_vector(avec, idx_a, afree); 00073 ((CSimpleFeatures<float64_t>*) rhs)->free_feature_vector(bvec, idx_b, bfree); 00074 00075 00076 // trap division by zero 00077 if(s==0 || nx==0 || ny==0) 00078 return 0; 00079 00080 d/=CMath::sqrt(nx*ny); 00081 00082 // can only happen due to numerical problems 00083 if (CMath::abs(d)>1.0) 00084 d=CMath::sign(d); 00085 00086 return acos(d); 00087 }