PolyMatchWordStringKernel.cpp

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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 "lib/common.h"
00012 #include "lib/io.h"
00013 #include "kernel/PolyMatchWordStringKernel.h"
00014 #include "kernel/SqrtDiagKernelNormalizer.h"
00015 #include "features/Features.h"
00016 #include "features/StringFeatures.h"
00017 
00018 using namespace shogun;
00019 
00020 CPolyMatchWordStringKernel::CPolyMatchWordStringKernel(int32_t size, int32_t d, bool i)
00021 : CStringKernel<uint16_t>(size),degree(d),inhomogene(i)
00022 {
00023     set_normalizer(new CSqrtDiagKernelNormalizer());
00024 }
00025 
00026 CPolyMatchWordStringKernel::CPolyMatchWordStringKernel(
00027     CStringFeatures<uint16_t>* l, CStringFeatures<uint16_t>* r, int32_t d, bool i)
00028 : CStringKernel<uint16_t>(10),degree(d),inhomogene(i)
00029 {
00030     set_normalizer(new CSqrtDiagKernelNormalizer());
00031     init(l, r);
00032 }
00033 
00034 CPolyMatchWordStringKernel::~CPolyMatchWordStringKernel()
00035 {
00036     cleanup();
00037 }
00038 
00039 bool CPolyMatchWordStringKernel::init(CFeatures* l, CFeatures* r)
00040 {
00041     CStringKernel<uint16_t>::init(l,r);
00042     return init_normalizer();
00043 }
00044 
00045 void CPolyMatchWordStringKernel::cleanup()
00046 {
00047     CKernel::cleanup();
00048 }
00049 
00050 float64_t CPolyMatchWordStringKernel::compute(int32_t idx_a, int32_t idx_b)
00051 {
00052     int32_t alen, blen;
00053     bool free_avec, free_bvec;
00054 
00055     uint16_t* avec=((CStringFeatures<uint16_t>*) lhs)->get_feature_vector(idx_a, alen, free_avec);
00056     uint16_t* bvec=((CStringFeatures<uint16_t>*) rhs)->get_feature_vector(idx_b, blen, free_bvec);
00057 
00058     ASSERT(alen==blen);
00059 
00060     int32_t sum=0;
00061 
00062     for (int32_t i=0; i<alen; i++)
00063         sum+= (avec[i]==bvec[i]) ? 1 : 0;
00064 
00065     if (inhomogene)
00066         sum+=1;
00067 
00068     float64_t result=sum;
00069 
00070     for (int32_t j=1; j<degree; j++)
00071         result*=sum;
00072 
00073     ((CStringFeatures<uint16_t>*) lhs)->free_feature_vector(avec, idx_a, free_avec);
00074     ((CStringFeatures<uint16_t>*) rhs)->free_feature_vector(bvec, idx_b, free_bvec);
00075     return result;
00076 }

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