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| 1 | +#ifndef __LTP_FRAMEWORK_DECODER_H__ |
| 2 | +#define __LTP_FRAMEWORK_DECODER_H__ |
| 3 | + |
| 4 | +#include "utils/math/mat.h" |
| 5 | +#include "utils/math/sparsevec.h" |
| 6 | +#include "utils/math/featurevec.h" |
| 7 | + |
| 8 | +namespace ltp { |
| 9 | +namespace framework { |
| 10 | + |
| 11 | +struct ViterbiLatticeItem { |
| 12 | + ViterbiLatticeItem (const size_t& _i, const size_t& _l, const double& _score, |
| 13 | + const ViterbiLatticeItem* _prev) |
| 14 | + : i(_i), l(_l), score(_score), prev(_prev) {} |
| 15 | + |
| 16 | + ViterbiLatticeItem (const size_t& _l, const double& _score) |
| 17 | + : i(0), l(_l), score(_score), prev(0) {} |
| 18 | + |
| 19 | + size_t i; |
| 20 | + size_t l; |
| 21 | + double score; |
| 22 | + const ViterbiLatticeItem* prev; |
| 23 | +}; |
| 24 | + |
| 25 | +class ViterbiDecodeConstrain { |
| 26 | +public: |
| 27 | + virtual bool can_emit(const size_t& i, const size_t& j) const { |
| 28 | + return true; |
| 29 | + } |
| 30 | + |
| 31 | + virtual bool can_tran(const size_t& i, const size_t& j) const { |
| 32 | + return true; |
| 33 | + } |
| 34 | +}; |
| 35 | + |
| 36 | +class ViterbiFeatureContext { |
| 37 | +public: |
| 38 | + math::SparseVec correct_features; //! the gold features. |
| 39 | + math::SparseVec predict_features; //! the predicted features. |
| 40 | + math::Mat<math::FeatureVector*> uni_features; //! the feature cache. |
| 41 | + |
| 42 | + ViterbiFeatureContext() {} |
| 43 | + ~ViterbiFeatureContext() { clear(); } |
| 44 | + |
| 45 | + void clear() { |
| 46 | + if (uni_features.total_size() > 0) { |
| 47 | + size_t d1 = uni_features.nrows(); |
| 48 | + size_t d2 = uni_features.ncols(); |
| 49 | + for (size_t i = 0; i < d1; ++ i) { |
| 50 | + if (uni_features[i][0]) { |
| 51 | + uni_features[i][0]->clear(); |
| 52 | + } |
| 53 | + for (size_t j = 0; j < d2; ++j) { |
| 54 | + if (uni_features[i][j]) { |
| 55 | + delete uni_features[i][j]; |
| 56 | + } |
| 57 | + } |
| 58 | + } |
| 59 | + } |
| 60 | + |
| 61 | + uni_features.dealloc(); |
| 62 | + correct_features.zero(); |
| 63 | + predict_features.zero(); |
| 64 | + } // end clear |
| 65 | +}; |
| 66 | + |
| 67 | +class ViterbiScoreMatrix { |
| 68 | +private: |
| 69 | + math::Mat< double > emit_scores; |
| 70 | + math::Mat< double > tran_scores; |
| 71 | +public: |
| 72 | + ViterbiScoreMatrix() {} |
| 73 | + ViterbiScoreMatrix(const size_t& L, const size_t& T) { |
| 74 | + emit_scores.resize(L, T); |
| 75 | + tran_scores.resize(T, T); |
| 76 | + } |
| 77 | + |
| 78 | + ~ViterbiScoreMatrix() {} |
| 79 | + |
| 80 | + void clear() { |
| 81 | + emit_scores.dealloc(); |
| 82 | + tran_scores.dealloc(); |
| 83 | + } |
| 84 | + |
| 85 | + void resize(const size_t& L, const size_t& T) { |
| 86 | + emit_scores.resize(L, T); |
| 87 | + tran_scores.resize(T, T); |
| 88 | + } |
| 89 | + |
| 90 | + void resize(const size_t& L, const size_t& T, const double& V) { |
| 91 | + emit_scores.resize(L, T); emit_scores = V; |
| 92 | + tran_scores.resize(T, T); tran_scores = V; |
| 93 | + } |
| 94 | + |
| 95 | + size_t labels() const { |
| 96 | + return emit_scores.ncols(); |
| 97 | + } |
| 98 | + |
| 99 | + size_t length() const { |
| 100 | + return emit_scores.nrows(); |
| 101 | + } |
| 102 | + |
| 103 | + double emit(const size_t& i, const size_t& j) const { |
| 104 | + return emit_scores[i][j]; |
| 105 | + } |
| 106 | + |
| 107 | + double tran(const size_t& i, const size_t& j) const { |
| 108 | + return tran_scores[i][j]; |
| 109 | + } |
| 110 | + |
| 111 | + double safe_emit(const size_t& i, const size_t& j, |
| 112 | + const double& default_retval = 0.) const { |
| 113 | + if (i >= emit_scores.nrows() || j >= tran_scores.ncols()) { |
| 114 | + return default_retval; |
| 115 | + } |
| 116 | + return emit_scores[i][j]; |
| 117 | + } |
| 118 | + |
| 119 | + double safe_tran(const size_t& i, const size_t& j, |
| 120 | + const double& default_retval = 0.) const { |
| 121 | + if (i >= tran_scores.nrows() || j >= tran_scores.ncols()) { |
| 122 | + return default_retval; |
| 123 | + } |
| 124 | + return tran_scores[i][j]; |
| 125 | + } |
| 126 | + |
| 127 | + void set_emit(const size_t& i, const size_t& j, const double& score) { |
| 128 | + emit_scores[i][j] = score; |
| 129 | + } |
| 130 | + |
| 131 | + void set_tran(const size_t& i, const size_t& j, const double& score) { |
| 132 | + tran_scores[i][j] = score; |
| 133 | + } |
| 134 | + |
| 135 | + void safe_set_emit(const size_t& i, const size_t& j, const double& score) { |
| 136 | + if (i >= emit_scores.nrows() || j >= tran_scores.ncols()) { |
| 137 | + return; |
| 138 | + } |
| 139 | + emit_scores[i][j] = score; |
| 140 | + } |
| 141 | + |
| 142 | + void safe_set_tran(const size_t& i, const size_t& j, const double& score) { |
| 143 | + if (i >= tran_scores.nrows() || j >= tran_scores.ncols()) { |
| 144 | + return; |
| 145 | + } |
| 146 | + tran_scores[i][j] = score; |
| 147 | + } |
| 148 | +}; |
| 149 | + |
| 150 | +class ViterbiDecoder { |
| 151 | +public: |
| 152 | + void decode(const ViterbiScoreMatrix& scm, std::vector<int>& output) { |
| 153 | + size_t L = scm.length(); |
| 154 | + size_t T = scm.labels(); |
| 155 | + |
| 156 | + init_lattice(L, T); |
| 157 | + |
| 158 | + for (size_t i = 0; i < L; ++ i) { |
| 159 | + for (size_t t = 0; t < T; ++ t) { |
| 160 | + if (i == 0) { |
| 161 | + ViterbiLatticeItem* item = new ViterbiLatticeItem(i, t, scm.emit(i, t), NULL); |
| 162 | + lattice_insert(lattice[i][t], item); |
| 163 | + } else { |
| 164 | + for (size_t pt = 0; pt < T; ++ pt) { |
| 165 | + const ViterbiLatticeItem* prev = lattice[i-1][pt]; |
| 166 | + if (!prev) { continue; } |
| 167 | + |
| 168 | + double s = scm.emit(i, t) + scm.tran(pt, t) + prev->score; |
| 169 | + ViterbiLatticeItem* item = new ViterbiLatticeItem(i, t, s, prev); |
| 170 | + lattice_insert(lattice[i][t], item); |
| 171 | + } |
| 172 | + } |
| 173 | + } |
| 174 | + } |
| 175 | + |
| 176 | + get_result(L-1, output); |
| 177 | + free_lattice(); |
| 178 | + } |
| 179 | + |
| 180 | + void decode(const ViterbiScoreMatrix& scm, |
| 181 | + const ViterbiDecodeConstrain& con, |
| 182 | + std::vector<int>& output) { |
| 183 | + size_t L = scm.length(); |
| 184 | + size_t T = scm.labels(); |
| 185 | + |
| 186 | + init_lattice(L, T); |
| 187 | + |
| 188 | + for (size_t i = 0; i < L; ++ i) { |
| 189 | + for (size_t t = 0; t < T; ++ t) { |
| 190 | + if (!con.can_emit(i, t)) { continue; } |
| 191 | + |
| 192 | + if (i == 0) { |
| 193 | + ViterbiLatticeItem* item = new ViterbiLatticeItem(i, t, scm.emit(i, t), NULL); |
| 194 | + lattice_insert(lattice[i][t], item); |
| 195 | + } else { |
| 196 | + for (size_t pt = 0; pt < T; ++ pt) { |
| 197 | + if (!con.can_emit(i-1, pt) || !con.can_tran(pt, t)) { continue; } |
| 198 | + |
| 199 | + const ViterbiLatticeItem* prev = lattice[i-1][pt]; |
| 200 | + if (!prev) { continue; } |
| 201 | + |
| 202 | + double s = scm.emit(i, t) + scm.tran(pt, t) + prev->score; |
| 203 | + ViterbiLatticeItem* item = new ViterbiLatticeItem(i, t, s, prev); |
| 204 | + lattice_insert(lattice[i][t], item); |
| 205 | + } |
| 206 | + } |
| 207 | + } |
| 208 | + } |
| 209 | + get_result(L-1, output); |
| 210 | + free_lattice(); |
| 211 | + } |
| 212 | +protected: |
| 213 | + void init_lattice(const size_t& L, const size_t& T) { |
| 214 | + lattice.resize(L, T); |
| 215 | + lattice = NULL; |
| 216 | + } |
| 217 | + |
| 218 | + void get_result(std::vector<int>& output) { |
| 219 | + size_t L = lattice.nrows(); |
| 220 | + get_result(L- 1, output); |
| 221 | + } |
| 222 | + |
| 223 | + void get_result(const size_t& p, std::vector<int>& output) { |
| 224 | + size_t T = lattice.ncols(); |
| 225 | + |
| 226 | + const ViterbiLatticeItem* best = NULL; |
| 227 | + for (size_t t = 0; t < T; ++ t) { |
| 228 | + if (!lattice[p][t]) { |
| 229 | + continue; |
| 230 | + } |
| 231 | + |
| 232 | + if (best == NULL || lattice[p][t]->score > best->score) { |
| 233 | + best = lattice[p][t]; |
| 234 | + } |
| 235 | + } |
| 236 | + |
| 237 | + output.resize(p+1); |
| 238 | + while (best) { |
| 239 | + output[best->i] = best->l; |
| 240 | + best = best->prev; |
| 241 | + } |
| 242 | + } |
| 243 | + |
| 244 | + void free_lattice() { |
| 245 | + size_t L = lattice.total_size(); |
| 246 | + const ViterbiLatticeItem ** p = lattice.c_buf(); |
| 247 | + for (size_t i = 0; i < L; ++ i) { |
| 248 | + if (p[i]) { |
| 249 | + delete p[i]; |
| 250 | + p[i] = 0; |
| 251 | + } |
| 252 | + } |
| 253 | + } |
| 254 | + |
| 255 | + void lattice_insert(const ViterbiLatticeItem* &position, |
| 256 | + const ViterbiLatticeItem * const item) { |
| 257 | + if (position == NULL) { |
| 258 | + position = item; |
| 259 | + } else if (position->score < item->score) { |
| 260 | + delete position; |
| 261 | + position = item; |
| 262 | + } else { |
| 263 | + delete item; |
| 264 | + } |
| 265 | + } |
| 266 | + |
| 267 | + math::Mat< const ViterbiLatticeItem * > lattice; |
| 268 | +}; |
| 269 | + |
| 270 | +} // namespace framework |
| 271 | +} // namespace ltp |
| 272 | + |
| 273 | +#endif // end for __LTP_FRAMEWORK_DECODER_H__ |
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