ChiSquareDistance.cpp

Go to the documentation of this file.
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/ChiSquareDistance.h>
00015 #include <shogun/features/Features.h>
00016 #include <shogun/features/SimpleFeatures.h>
00017 
00018 using namespace shogun;
00019 
00020 CChiSquareDistance::CChiSquareDistance() : CSimpleDistance<float64_t>()
00021 {
00022 }
00023 
00024 CChiSquareDistance::CChiSquareDistance(CSimpleFeatures<float64_t>* l, CSimpleFeatures<float64_t>* r)
00025 : CSimpleDistance<float64_t>()
00026 {
00027     init(l, r);
00028 }
00029 
00030 CChiSquareDistance::~CChiSquareDistance()
00031 {
00032     cleanup();
00033 }
00034 
00035 bool CChiSquareDistance::init(CFeatures* l, CFeatures* r)
00036 {
00037     bool result=CSimpleDistance<float64_t>::init(l,r);
00038 
00039     return result;
00040 }
00041 
00042 void CChiSquareDistance::cleanup()
00043 {
00044 }
00045 
00046 float64_t CChiSquareDistance::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 absTmp = 0;
00059     float64_t result=0;
00060     {
00061         for (int32_t i=0; i<alen; i++)
00062         {
00063             absTmp=fabs(avec[i])+fabs(bvec[i]);
00064             if(absTmp!=0)
00065                 result+=pow((avec[i]-bvec[i]),2)/absTmp;
00066         }
00067 
00068     }
00069 
00070     ((CSimpleFeatures<float64_t>*) lhs)->free_feature_vector(avec, idx_a, afree);
00071     ((CSimpleFeatures<float64_t>*) rhs)->free_feature_vector(bvec, idx_b, bfree);
00072     
00073     return result;
00074 }
 All Classes Namespaces Files Functions Variables Typedefs Enumerations Enumerator Friends Defines

SHOGUN Machine Learning Toolbox - Documentation