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00011 #include "features/HashedWDFeatures.h"
00012 #include "lib/io.h"
00013
00014 using namespace shogun;
00015
00016 CHashedWDFeatures::CHashedWDFeatures(CStringFeatures<uint8_t>* str,
00017 int32_t start_order, int32_t order, int32_t from_order,
00018 int32_t hash_bits) : CDotFeatures()
00019 {
00020 ASSERT(start_order>=0);
00021 ASSERT(start_order<order);
00022 ASSERT(order<=from_order);
00023 ASSERT(hash_bits>0);
00024 ASSERT(str);
00025 ASSERT(str->have_same_length());
00026 SG_REF(str);
00027
00028 strings=str;
00029 string_length=str->get_max_vector_length();
00030 num_strings=str->get_num_vectors();
00031 CAlphabet* alpha=str->get_alphabet();
00032 alphabet_size=alpha->get_num_symbols();
00033 SG_UNREF(alpha);
00034
00035 degree=order;
00036 start_degree=start_order;
00037 from_degree=from_order;
00038 m_hash_bits=hash_bits;
00039 set_wd_weights();
00040 set_normalization_const();
00041 }
00042
00043 CHashedWDFeatures::CHashedWDFeatures(const CHashedWDFeatures& orig)
00044 : CDotFeatures(orig), strings(orig.strings),
00045 degree(orig.degree), start_degree(orig.start_degree),
00046 from_degree(orig.from_degree), m_hash_bits(orig.m_hash_bits),
00047 normalization_const(orig.normalization_const)
00048 {
00049 SG_REF(strings);
00050 string_length=strings->get_max_vector_length();
00051 num_strings=strings->get_num_vectors();
00052 CAlphabet* alpha=strings->get_alphabet();
00053 alphabet_size=alpha->get_num_symbols();
00054 SG_UNREF(alpha);
00055
00056 set_wd_weights();
00057 }
00058
00059 CHashedWDFeatures::~CHashedWDFeatures()
00060 {
00061 SG_UNREF(strings);
00062 delete[] wd_weights;
00063 }
00064
00065 float64_t CHashedWDFeatures::dot(int32_t vec_idx1, int32_t vec_idx2)
00066 {
00067 int32_t len1, len2;
00068 bool free_vec1, free_vec2;
00069
00070 uint8_t* vec1=strings->get_feature_vector(vec_idx1, len1, free_vec1);
00071 uint8_t* vec2=strings->get_feature_vector(vec_idx2, len2, free_vec2);
00072
00073 ASSERT(len1==len2);
00074
00075 float64_t sum=0.0;
00076
00077 for (int32_t i=0; i<len1; i++)
00078 {
00079 for (int32_t j=0; (i+j<len1) && (j<degree); j++)
00080 {
00081 if (vec1[i+j]!=vec2[i+j])
00082 break;
00083 if (j>=start_degree)
00084 sum += wd_weights[j]*wd_weights[j];
00085 }
00086 }
00087 strings->free_feature_vector(vec1, vec_idx1, free_vec1);
00088 strings->free_feature_vector(vec2, vec_idx2, free_vec2);
00089 return sum/CMath::sq(normalization_const);
00090 }
00091
00092 float64_t CHashedWDFeatures::dense_dot(int32_t vec_idx1, const float64_t* vec2, int32_t vec2_len)
00093 {
00094 if (vec2_len != w_dim)
00095 SG_ERROR("Dimensions don't match, vec2_dim=%d, w_dim=%d\n", vec2_len, w_dim);
00096
00097 float64_t sum=0;
00098 int32_t lim=CMath::min(degree, string_length);
00099 int32_t len;
00100 bool free_vec1;
00101 uint8_t* vec = strings->get_feature_vector(vec_idx1, len, free_vec1);
00102 uint32_t* val=new uint32_t[len];
00103
00104 uint32_t offs=0;
00105
00106 if (start_degree>0)
00107 {
00108
00109 for (int32_t i=0; i+start_degree < len; i++)
00110 val[i]=CHash::MurmurHash2(&vec[i], start_degree, 0xDEADBEAF);
00111 }
00112 else
00113 CMath::fill_vector(val, len, 0xDEADBEAF);
00114
00115 for (int32_t k=start_degree; k<lim; k++)
00116 {
00117 float64_t wd = wd_weights[k];
00118
00119 uint32_t o=offs;
00120 for (int32_t i=0; i+k < len; i++)
00121 {
00122 const uint32_t h=CHash::IncrementalMurmurHash2(vec[i+k], val[i]);
00123 val[i]=h;
00124 #ifdef DEBUG_HASHEDWD
00125 SG_PRINT("vec[i]=%d, k=%d, offs=%d o=%d h=%d \n", vec[i], k,offs, o, h);
00126 #endif
00127 sum+=vec2[o+(h & mask)]*wd;
00128 o+=partial_w_dim;
00129 }
00130 offs+=partial_w_dim*len;
00131 }
00132 delete[] val;
00133 strings->free_feature_vector(vec, vec_idx1, free_vec1);
00134
00135 return sum/normalization_const;
00136 }
00137
00138 void CHashedWDFeatures::add_to_dense_vec(float64_t alpha, int32_t vec_idx1, float64_t* vec2, int32_t vec2_len, bool abs_val)
00139 {
00140 if (vec2_len != w_dim)
00141 SG_ERROR("Dimensions don't match, vec2_dim=%d, w_dim=%d\n", vec2_len, w_dim);
00142
00143 int32_t lim=CMath::min(degree, string_length);
00144 int32_t len;
00145 bool free_vec1;
00146 uint8_t* vec = strings->get_feature_vector(vec_idx1, len, free_vec1);
00147 uint32_t* val=new uint32_t[len];
00148
00149 uint32_t offs=0;
00150
00151 if (start_degree>0)
00152 {
00153
00154 for (int32_t i=0; i+start_degree < len; i++)
00155 val[i]=CHash::MurmurHash2(&vec[i], start_degree, 0xDEADBEAF);
00156 }
00157 else
00158 CMath::fill_vector(val, len, 0xDEADBEAF);
00159
00160 for (int32_t k=start_degree; k<lim; k++)
00161 {
00162 float64_t wd = alpha*wd_weights[k]/normalization_const;
00163
00164 if (abs_val)
00165 wd=CMath::abs(wd);
00166
00167 uint32_t o=offs;
00168 for (int32_t i=0; i+k < len; i++)
00169 {
00170 const uint32_t h=CHash::IncrementalMurmurHash2(vec[i+k], val[i]);
00171 val[i]=h;
00172
00173 #ifdef DEBUG_HASHEDWD
00174 SG_PRINT("offs=%d o=%d h=%d \n", offs, o, h);
00175 SG_PRINT("vec[i]=%d, k=%d, offs=%d o=%d h=%d \n", vec[i], k,offs, o, h);
00176 #endif
00177 vec2[o+(h & mask)]+=wd;
00178 o+=partial_w_dim;
00179 }
00180 offs+=partial_w_dim*len;
00181 }
00182
00183 delete[] val;
00184 strings->free_feature_vector(vec, vec_idx1, free_vec1);
00185 }
00186
00187 void CHashedWDFeatures::set_wd_weights()
00188 {
00189 ASSERT(degree>0);
00190
00191 mask=(uint32_t) (((uint64_t) 1)<<m_hash_bits)-1;
00192 partial_w_dim=1<<m_hash_bits;
00193 w_dim=partial_w_dim*string_length*(degree-start_degree);
00194
00195 wd_weights=new float64_t[degree];
00196
00197 for (int32_t i=0; i<degree; i++)
00198 wd_weights[i]=sqrt(2.0*(from_degree-i)/(from_degree*(from_degree+1)));
00199
00200 SG_DEBUG("created HashedWDFeatures with d=%d (%d), alphabetsize=%d, "
00201 "dim=%d partial_dim=%d num=%d, len=%d\n",
00202 degree, from_degree, alphabet_size,
00203 w_dim, partial_w_dim, num_strings, string_length);
00204 }
00205
00206
00207 void CHashedWDFeatures::set_normalization_const(float64_t n)
00208 {
00209 if (n==0)
00210 {
00211 normalization_const=0;
00212 for (int32_t i=0; i<degree; i++)
00213 normalization_const+=(string_length-i)*wd_weights[i]*wd_weights[i];
00214
00215 normalization_const=CMath::sqrt(normalization_const);
00216 }
00217 else
00218 normalization_const=n;
00219
00220 SG_DEBUG("normalization_const:%f\n", normalization_const);
00221 }
00222
00223 CFeatures* CHashedWDFeatures::duplicate() const
00224 {
00225 return new CHashedWDFeatures(*this);
00226 }