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00011 #include <shogun/lib/common.h>
00012 #include <shogun/io/SGIO.h>
00013 #include <shogun/kernel/PolyMatchStringKernel.h>
00014 #include <shogun/kernel/SqrtDiagKernelNormalizer.h>
00015 #include <shogun/features/Features.h>
00016 #include <shogun/features/StringFeatures.h>
00017
00018 using namespace shogun;
00019
00020 CPolyMatchStringKernel::CPolyMatchStringKernel()
00021 : CStringKernel<char>()
00022 {
00023 init();
00024 }
00025
00026 CPolyMatchStringKernel::CPolyMatchStringKernel(int32_t size, int32_t d, bool i)
00027 : CStringKernel<char>(size)
00028 {
00029 init();
00030
00031 degree=d;
00032 inhomogene=i;
00033 }
00034
00035 CPolyMatchStringKernel::CPolyMatchStringKernel(
00036 CStringFeatures<char>* l, CStringFeatures<char>* r, int32_t d, bool i)
00037 : CStringKernel<char>(10)
00038 {
00039 init();
00040
00041 degree=d;
00042 inhomogene=i;
00043
00044 init(l, r);
00045 }
00046
00047 CPolyMatchStringKernel::~CPolyMatchStringKernel()
00048 {
00049 cleanup();
00050 }
00051
00052 bool CPolyMatchStringKernel::init(CFeatures* l, CFeatures* r)
00053 {
00054 CStringKernel<char>::init(l, r);
00055 return init_normalizer();
00056 }
00057
00058 void CPolyMatchStringKernel::cleanup()
00059 {
00060 CKernel::cleanup();
00061 }
00062
00063 float64_t CPolyMatchStringKernel::compute(int32_t idx_a, int32_t idx_b)
00064 {
00065 int32_t i, alen, blen, sum;
00066 bool free_avec, free_bvec;
00067
00068 char* avec = ((CStringFeatures<char>*) lhs)->get_feature_vector(idx_a, alen, free_avec);
00069 char* bvec = ((CStringFeatures<char>*) rhs)->get_feature_vector(idx_b, blen, free_bvec);
00070
00071 ASSERT(alen==blen);
00072 for (i = 0, sum = inhomogene; i<alen; i++)
00073 {
00074 if (avec[i]==bvec[i])
00075 sum++;
00076 }
00077 float64_t result = ((float64_t) sum);
00078
00079 if (rescaling)
00080 result/=alen;
00081
00082 ((CStringFeatures<char>*) lhs)->free_feature_vector(avec, idx_a, free_avec);
00083 ((CStringFeatures<char>*) rhs)->free_feature_vector(bvec, idx_b, free_bvec);
00084 return CMath::pow(result , degree);
00085 }
00086
00087 void CPolyMatchStringKernel::init()
00088 {
00089 degree=0;
00090 inhomogene=false;
00091 rescaling=false;
00092 set_normalizer(new CSqrtDiagKernelNormalizer());
00093
00094 m_parameters->add(°ree, "degree", "Degree of poly-kernel.");
00095 m_parameters->add(&inhomogene, "inhomogene", "True for inhomogene poly-kernel.");
00096 m_parameters->add(&rescaling, "rescaling", "True to rescale kernel with string length.");
00097 }