FixedDegreeStringKernel.cpp
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00011 #include "lib/common.h"
00012 #include "kernel/FixedDegreeStringKernel.h"
00013 #include "kernel/SqrtDiagKernelNormalizer.h"
00014 #include "features/Features.h"
00015 #include "features/StringFeatures.h"
00016 #include "lib/io.h"
00017
00018 using namespace shogun;
00019
00020 CFixedDegreeStringKernel::CFixedDegreeStringKernel(int32_t size, int32_t d)
00021 : CStringKernel<char>(size), degree(d)
00022 {
00023 set_normalizer(new CSqrtDiagKernelNormalizer());
00024 }
00025
00026 CFixedDegreeStringKernel::CFixedDegreeStringKernel(
00027 CStringFeatures<char>* l, CStringFeatures<char>* r, int32_t d)
00028 : CStringKernel<char>(10), degree(d)
00029 {
00030 set_normalizer(new CSqrtDiagKernelNormalizer());
00031 init(l, r);
00032 }
00033
00034 CFixedDegreeStringKernel::~CFixedDegreeStringKernel()
00035 {
00036 cleanup();
00037 }
00038
00039 bool CFixedDegreeStringKernel::init(CFeatures* l, CFeatures* r)
00040 {
00041 CStringKernel<char>::init(l, r);
00042 return init_normalizer();
00043 }
00044
00045 void CFixedDegreeStringKernel::cleanup()
00046 {
00047 CKernel::cleanup();
00048 }
00049
00050 float64_t CFixedDegreeStringKernel::compute(int32_t idx_a, int32_t idx_b)
00051 {
00052 int32_t alen, blen;
00053 bool free_avec, free_bvec;
00054
00055 char* avec = ((CStringFeatures<char>*) lhs)->get_feature_vector(idx_a, alen, free_avec);
00056 char* bvec = ((CStringFeatures<char>*) rhs)->get_feature_vector(idx_b, blen, free_bvec);
00057
00058
00059 ASSERT(alen==blen);
00060
00061 int64_t sum = 0;
00062 for (int32_t i = 0; i<alen-degree+1; i++)
00063 {
00064 bool match = true;
00065
00066 for (int32_t j = i; j<i+degree && match; j++)
00067 match = avec[j]==bvec[j];
00068 if (match)
00069 sum++;
00070 }
00071 ((CStringFeatures<char>*) lhs)->free_feature_vector(avec, idx_a, free_avec);
00072 ((CStringFeatures<char>*) rhs)->free_feature_vector(bvec, idx_b, free_bvec);
00073
00074 return sum;
00075 }