SimpleLocalityImprovedStringKernel.cpp
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00011 #include "lib/common.h"
00012 #include "lib/io.h"
00013 #include "kernel/SimpleLocalityImprovedStringKernel.h"
00014 #include "features/Features.h"
00015 #include "features/StringFeatures.h"
00016
00017 CSimpleLocalityImprovedStringKernel::CSimpleLocalityImprovedStringKernel(
00018 int32_t size, int32_t l, int32_t id, int32_t od)
00019 : CStringKernel<char>(size), length(l), inner_degree(id), outer_degree(od),
00020 pyramid_weights(NULL)
00021 {
00022 }
00023
00024 CSimpleLocalityImprovedStringKernel::CSimpleLocalityImprovedStringKernel(
00025 CStringFeatures<char>* l, CStringFeatures<char>* r,
00026 int32_t len, int32_t id, int32_t od)
00027 : CStringKernel<char>(10), length(len), inner_degree(id), outer_degree(od),
00028 pyramid_weights(NULL)
00029 {
00030 init(l, r);
00031 }
00032
00033 CSimpleLocalityImprovedStringKernel::~CSimpleLocalityImprovedStringKernel()
00034 {
00035 cleanup();
00036 }
00037
00038 bool CSimpleLocalityImprovedStringKernel::init(CFeatures* l, CFeatures* r)
00039 {
00040 bool result = CStringKernel<char>::init(l,r);
00041
00042 if (!result)
00043 return false;
00044 int32_t num_features = ((CStringFeatures<char>*) l)->get_max_vector_length();
00045 pyramid_weights = new float64_t[num_features];
00046 ASSERT(pyramid_weights);
00047 SG_INFO("initializing pyramid weights: size=%ld length=%i\n",
00048 num_features, length);
00049
00050 const int32_t PYRAL = 2 * length - 1;
00051 float64_t PYRAL_pot;
00052 int32_t DEGREE1_1 = (inner_degree & 0x1)==0;
00053 int32_t DEGREE1_1n = (inner_degree & ~0x1)!=0;
00054 int32_t DEGREE1_2 = (inner_degree & 0x2)!=0;
00055 int32_t DEGREE1_3 = (inner_degree & ~0x3)!=0;
00056 int32_t DEGREE1_4 = (inner_degree & 0x4)!=0;
00057 {
00058 float64_t PYRAL_ = PYRAL;
00059 PYRAL_pot = DEGREE1_1 ? 1.0 : PYRAL_;
00060 if (DEGREE1_1n)
00061 {
00062 PYRAL_ *= PYRAL_;
00063 if (DEGREE1_2)
00064 PYRAL_pot *= PYRAL_;
00065 if (DEGREE1_3)
00066 {
00067 PYRAL_ *= PYRAL_;
00068 if (DEGREE1_4)
00069 PYRAL_pot *= PYRAL_;
00070 }
00071 }
00072 }
00073
00074 int32_t pyra_len = num_features-PYRAL+1;
00075 int32_t pyra_len2 = (int32_t) pyra_len/2;
00076 {
00077 int32_t j;
00078 for (j = 0; j < pyra_len; j++)
00079 pyramid_weights[j] = 4*((float64_t)((j < pyra_len2)? j+1 : pyra_len-j))/((float64_t)pyra_len);
00080 for (j = 0; j < pyra_len; j++)
00081 pyramid_weights[j] /= PYRAL_pot;
00082 }
00083
00084 return init_normalizer();
00085 }
00086
00087 void CSimpleLocalityImprovedStringKernel::cleanup()
00088 {
00089 delete[] pyramid_weights;
00090 pyramid_weights = NULL;
00091
00092 CKernel::cleanup();
00093 }
00094
00095 bool CSimpleLocalityImprovedStringKernel::load_init(FILE* src)
00096 {
00097 return false;
00098 }
00099
00100 bool CSimpleLocalityImprovedStringKernel::save_init(FILE* dest)
00101 {
00102 return false;
00103 }
00104
00105 float64_t CSimpleLocalityImprovedStringKernel::dot_pyr (const char* const x1,
00106 const char* const x2, const int32_t NOF_NTS, const int32_t NTWIDTH,
00107 const int32_t DEGREE1, const int32_t DEGREE2, float64_t *pyra)
00108 {
00109 const int32_t PYRAL = 2*NTWIDTH-1;
00110 int32_t pyra_len, pyra_len2;
00111 float64_t pot, PYRAL_pot;
00112 float64_t sum;
00113 int32_t DEGREE1_1 = (DEGREE1 & 0x1)==0;
00114 int32_t DEGREE1_1n = (DEGREE1 & ~0x1)!=0;
00115 int32_t DEGREE1_2 = (DEGREE1 & 0x2)!=0;
00116 int32_t DEGREE1_3 = (DEGREE1 & ~0x3)!=0;
00117 int32_t DEGREE1_4 = (DEGREE1 & 0x4)!=0;
00118 {
00119 float64_t PYRAL_ = PYRAL;
00120 PYRAL_pot = DEGREE1_1 ? 1.0 : PYRAL_;
00121 if (DEGREE1_1n)
00122 {
00123 PYRAL_ *= PYRAL_;
00124 if (DEGREE1_2) PYRAL_pot *= PYRAL_;
00125 if (DEGREE1_3)
00126 {
00127 PYRAL_ *= PYRAL_;
00128 if (DEGREE1_4) PYRAL_pot *= PYRAL_;
00129 }
00130 }
00131 }
00132
00133 ASSERT((DEGREE1 & ~0x7) == 0);
00134 ASSERT((DEGREE2 & ~0x7) == 0);
00135
00136 pyra_len = NOF_NTS-PYRAL+1;
00137 pyra_len2 = (int32_t) pyra_len/2;
00138 {
00139 int32_t j;
00140 for (j = 0; j < pyra_len; j++)
00141 pyra[j] = 4*((float64_t)((j < pyra_len2) ? j+1 : pyra_len-j))/((float64_t)pyra_len);
00142 for (j = 0; j < pyra_len; j++)
00143 pyra[j] /= PYRAL_pot;
00144 }
00145
00146 register int32_t conv;
00147 register int32_t i;
00148 register int32_t j;
00149
00150 sum = 0.0;
00151 conv = 0;
00152 for (j = 0; j < PYRAL; j++)
00153 conv += (x1[j] == x2[j]) ? 1 : 0;
00154
00155 for (i = 0; i < NOF_NTS-PYRAL+1; i++)
00156 {
00157 register float64_t pot2;
00158 if (i>0)
00159 conv += ((x1[i+PYRAL-1] == x2[i+PYRAL-1]) ? 1 : 0 ) -
00160 ((x1[i-1] == x2[i-1]) ? 1 : 0);
00161 {
00162 register float64_t conv2 = conv;
00163 pot2 = (DEGREE1_1) ? 1.0 : conv2;
00164 if (DEGREE1_1n)
00165 {
00166 conv2 *= conv2;
00167 if (DEGREE1_2)
00168 pot2 *= conv2;
00169 if (DEGREE1_3 && DEGREE1_4)
00170 pot2 *= conv2*conv2;
00171 }
00172 }
00173 sum += pot2*pyra[i];
00174 }
00175
00176 pot = ((DEGREE2 & 0x1) == 0) ? 1.0 : sum;
00177 if ((DEGREE2 & ~0x1) != 0)
00178 {
00179 sum *= sum;
00180 if ((DEGREE2 & 0x2) != 0)
00181 pot *= sum;
00182 if ((DEGREE2 & ~0x3) != 0)
00183 {
00184 sum *= sum;
00185 if ((DEGREE2 & 0x4) != 0)
00186 pot *= sum;
00187 }
00188 }
00189 return pot;
00190 }
00191
00192 float64_t CSimpleLocalityImprovedStringKernel::compute(
00193 int32_t idx_a, int32_t idx_b)
00194 {
00195 int32_t alen, blen;
00196
00197 char* avec = ((CStringFeatures<char>*) lhs)->get_feature_vector(idx_a, alen);
00198 char* bvec = ((CStringFeatures<char>*) rhs)->get_feature_vector(idx_b, blen);
00199
00200
00201 ASSERT(alen==blen);
00202
00203 float64_t dpt;
00204
00205 dpt = dot_pyr(avec, bvec, alen, length, inner_degree, outer_degree, pyramid_weights);
00206 dpt = dpt / pow((float64_t)alen, (float64_t)outer_degree);
00207 return (float64_t) dpt;
00208 }