| /* |
| * Copyright (C) 2013, The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| #ifndef LATINIME_PROBABILITY_UTILS_H |
| #define LATINIME_PROBABILITY_UTILS_H |
| |
| #include <stdint.h> |
| |
| #include "defines.h" |
| |
| namespace latinime { |
| |
| class ProbabilityUtils { |
| public: |
| static AK_FORCE_INLINE int backoff(const int unigramProbability) { |
| return unigramProbability; |
| // For some reason, applying the backoff weight gives bad results in tests. To apply the |
| // backoff weight, we divide the probability by 2, which in our storing format means |
| // decreasing the score by 8. |
| // TODO: figure out what's wrong with this. |
| // return unigramProbability > 8 ? |
| // unigramProbability - 8 : (0 == unigramProbability ? 0 : 8); |
| } |
| |
| static AK_FORCE_INLINE int computeProbabilityForBigram( |
| const int unigramProbability, const int bigramProbability) { |
| // We divide the range [unigramProbability..255] in 16.5 steps - in other words, we want |
| // the unigram probability to be the median value of the 17th step from the top. A value of |
| // 0 for the bigram probability represents the middle of the 16th step from the top, |
| // while a value of 15 represents the middle of the top step. |
| // See makedict.BinaryDictEncoder#makeBigramFlags for details. |
| const float stepSize = static_cast<float>(MAX_PROBABILITY - unigramProbability) |
| / (1.5f + MAX_BIGRAM_ENCODED_PROBABILITY); |
| return unigramProbability |
| + static_cast<int>(static_cast<float>(bigramProbability + 1) * stepSize); |
| } |
| |
| private: |
| DISALLOW_IMPLICIT_CONSTRUCTORS(ProbabilityUtils); |
| }; |
| } |
| #endif /* LATINIME_PROBABILITY_UTILS_H */ |