LinearStringKernel.cpp
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00011 #include "lib/common.h"
00012 #include "lib/io.h"
00013 #include "lib/Mathematics.h"
00014 #include "kernel/LinearStringKernel.h"
00015 #include "features/StringFeatures.h"
00016
00017 CLinearStringKernel::CLinearStringKernel()
00018 : CStringKernel<char>(0), normal(NULL)
00019 {
00020 }
00021
00022 CLinearStringKernel::CLinearStringKernel(
00023 CStringFeatures<char>* l, CStringFeatures<char>* r)
00024 : CStringKernel<char>(0), normal(NULL)
00025 {
00026 init(l, r);
00027 }
00028
00029 CLinearStringKernel::~CLinearStringKernel()
00030 {
00031 cleanup();
00032 }
00033
00034 bool CLinearStringKernel::init(CFeatures *l, CFeatures *r)
00035 {
00036 CStringKernel<char>::init(l, r);
00037 return init_normalizer();
00038 }
00039
00040 void CLinearStringKernel::cleanup()
00041 {
00042 delete_optimization();
00043
00044 CKernel::cleanup();
00045 }
00046
00047 bool CLinearStringKernel::load_init(FILE *src)
00048 {
00049 return false;
00050 }
00051
00052 bool CLinearStringKernel::save_init(FILE *dest)
00053 {
00054 return false;
00055 }
00056
00057 void CLinearStringKernel::clear_normal()
00058 {
00059 memset(normal, 0, lhs->get_num_vectors()*sizeof(float64_t));
00060 }
00061
00062 void CLinearStringKernel::add_to_normal(int32_t idx, float64_t weight)
00063 {
00064 int32_t vlen;
00065 char* vec = ((CStringFeatures<char>*) lhs)->get_feature_vector(idx, vlen);
00066
00067 for (int32_t i=0; i<vlen; i++)
00068 normal[i] += weight*normalizer->normalize_lhs(vec[i], idx);
00069 }
00070
00071 float64_t CLinearStringKernel::compute(int32_t idx_a, int32_t idx_b)
00072 {
00073 int32_t alen, blen;
00074
00075 char *avec = ((CStringFeatures<char>*) lhs)->get_feature_vector(idx_a, alen);
00076 char *bvec = ((CStringFeatures<char>*) rhs)->get_feature_vector(idx_b, blen);
00077
00078 ASSERT(alen==blen);
00079 return CMath::dot(avec, bvec, alen);
00080 }
00081
00082 bool CLinearStringKernel::init_optimization(
00083 int32_t num_suppvec, int32_t *sv_idx, float64_t *alphas)
00084 {
00085 int32_t i, alen;
00086
00087 int32_t num_feat = ((CStringFeatures<char>*) lhs)->get_max_vector_length();
00088 ASSERT(num_feat);
00089
00090 normal = new float64_t[num_feat];
00091 ASSERT(normal);
00092 clear_normal();
00093
00094 for (i = 0; i<num_suppvec; i++)
00095 {
00096 char *avec = ((CStringFeatures<char>*) lhs)->get_feature_vector(sv_idx[i], alen);
00097 ASSERT(avec);
00098
00099 for (int32_t j = 0; j<num_feat; j++)
00100 {
00101 normal[j] += alphas[i]*
00102 normalizer->normalize_lhs(((float64_t) avec[j]), sv_idx[i]);
00103 }
00104 }
00105 set_is_initialized(true);
00106 return true;
00107 }
00108
00109 bool CLinearStringKernel::delete_optimization()
00110 {
00111 delete[] normal;
00112 normal = NULL;
00113 set_is_initialized(false);
00114 return true;
00115 }
00116
00117 float64_t CLinearStringKernel::compute_optimized(int32_t idx_b)
00118 {
00119 int32_t blen;
00120 char* bvec = ((CStringFeatures<char>*) rhs)->get_feature_vector(idx_b, blen);
00121
00122 return normalizer->normalize_rhs(CMath::dot(normal, bvec, blen), idx_b);
00123 }