Merge "Add DynamicLanguageModelProbabilityUtils."
This commit is contained in:
Keisuke Kuroyanagi
Android (Google) Code Review
commit
04a492cb49
3 changed files with 152 additions and 0 deletions
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@ -71,6 +71,7 @@ LATIN_IME_CORE_SRC_FILES := \
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ver4_patricia_trie_writing_helper.cpp \
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ver4_pt_node_array_reader.cpp) \
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$(addprefix suggest/policyimpl/dictionary/structure/v4/content/, \
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dynamic_language_model_probability_utils.cpp \
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language_model_dict_content.cpp \
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language_model_dict_content_global_counters.cpp \
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shortcut_dict_content.cpp \
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@ -0,0 +1,37 @@
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/*
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* Copyright (C) 2014, The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "suggest/policyimpl/dictionary/structure/v4/content/dynamic_language_model_probability_utils.h"
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namespace latinime {
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// These counts are used to provide stable probabilities even if the user's input count is small.
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const int DynamicLanguageModelProbabilityUtils::ASSUMED_MIN_COUNT_FOR_UNIGRAMS = 8192;
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const int DynamicLanguageModelProbabilityUtils::ASSUMED_MIN_COUNT_FOR_BIGRAMS = 2;
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const int DynamicLanguageModelProbabilityUtils::ASSUMED_MIN_COUNT_FOR_TRIGRAMS = 2;
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// These are encoded backoff weights.
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// Note that we give positive value for trigrams that means the weight is more than 1.
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// TODO: Apply backoff for main dictionaries and quit giving a positive backoff weight.
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const int DynamicLanguageModelProbabilityUtils::ENCODED_BACKOFF_WEIGHT_FOR_UNIGRAMS = -32;
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const int DynamicLanguageModelProbabilityUtils::ENCODED_BACKOFF_WEIGHT_FOR_BIGRAMS = 0;
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const int DynamicLanguageModelProbabilityUtils::ENCODED_BACKOFF_WEIGHT_FOR_TRIGRAMS = 8;
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// This value is used to remove too old entries from the dictionary.
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const int DynamicLanguageModelProbabilityUtils::DURATION_TO_DISCARD_ENTRY_IN_SECONDS =
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300 * 24 * 60 * 60; // 300 days
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} // namespace latinime
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@ -0,0 +1,114 @@
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/*
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* Copyright (C) 2014, The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef LATINIME_DYNAMIC_LANGUAGE_MODEL_PROBABILITY_UTILS_H
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#define LATINIME_DYNAMIC_LANGUAGE_MODEL_PROBABILITY_UTILS_H
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#include <algorithm>
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#include "defines.h"
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#include "suggest/core/dictionary/property/historical_info.h"
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#include "utils/time_keeper.h"
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namespace latinime {
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class DynamicLanguageModelProbabilityUtils {
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public:
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static float computeRawProbabilityFromCounts(const int count, const int contextCount,
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const int matchedWordCountInContext) {
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int minCount = 0;
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switch (matchedWordCountInContext) {
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case 1:
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minCount = ASSUMED_MIN_COUNT_FOR_UNIGRAMS;
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break;
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case 2:
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minCount = ASSUMED_MIN_COUNT_FOR_BIGRAMS;
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break;
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case 3:
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minCount = ASSUMED_MIN_COUNT_FOR_TRIGRAMS;
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break;
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default:
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AKLOGE("computeRawProbabilityFromCounts is called with invalid "
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"matchedWordCountInContext (%d).", matchedWordCountInContext);
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ASSERT(false);
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return 0.0f;
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}
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return static_cast<float>(count) / static_cast<float>(std::max(contextCount, minCount));
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}
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static float backoff(const int ngramProbability, const int matchedWordCountInContext) {
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int probability = NOT_A_PROBABILITY;
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switch (matchedWordCountInContext) {
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case 1:
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probability = ngramProbability + ENCODED_BACKOFF_WEIGHT_FOR_UNIGRAMS;
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break;
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case 2:
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probability = ngramProbability + ENCODED_BACKOFF_WEIGHT_FOR_BIGRAMS;
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break;
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case 3:
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probability = ngramProbability + ENCODED_BACKOFF_WEIGHT_FOR_TRIGRAMS;
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break;
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default:
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AKLOGE("backoff is called with invalid matchedWordCountInContext (%d).",
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matchedWordCountInContext);
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ASSERT(false);
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return NOT_A_PROBABILITY;
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}
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return std::min(std::max(probability, NOT_A_PROBABILITY), MAX_PROBABILITY);
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}
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static int getDecayedProbability(const int probability, const HistoricalInfo historicalInfo) {
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const int elapsedTime = TimeKeeper::peekCurrentTime() - historicalInfo.getTimestamp();
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if (elapsedTime < 0) {
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AKLOGE("The elapsed time is negatime value. Timestamp overflow?");
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return NOT_A_PROBABILITY;
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}
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// TODO: Improve this logic.
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// We don't modify probability depending on the elapsed time.
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return probability;
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}
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static int shouldRemoveEntryDuringGC(const HistoricalInfo historicalInfo) {
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// TODO: Improve this logic.
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const int elapsedTime = TimeKeeper::peekCurrentTime() - historicalInfo.getTimestamp();
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return elapsedTime > DURATION_TO_DISCARD_ENTRY_IN_SECONDS;
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}
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static int getPriorityToPreventFromEviction(const HistoricalInfo historicalInfo) {
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// TODO: Improve this logic.
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// More recently input entries get higher priority.
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return historicalInfo.getTimestamp();
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}
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private:
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DISALLOW_IMPLICIT_CONSTRUCTORS(DynamicLanguageModelProbabilityUtils);
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static_assert(MAX_PREV_WORD_COUNT_FOR_N_GRAM <= 2, "Max supported Ngram is Trigram.");
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static const int ASSUMED_MIN_COUNT_FOR_UNIGRAMS;
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static const int ASSUMED_MIN_COUNT_FOR_BIGRAMS;
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static const int ASSUMED_MIN_COUNT_FOR_TRIGRAMS;
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static const int ENCODED_BACKOFF_WEIGHT_FOR_UNIGRAMS;
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static const int ENCODED_BACKOFF_WEIGHT_FOR_BIGRAMS;
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static const int ENCODED_BACKOFF_WEIGHT_FOR_TRIGRAMS;
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static const int DURATION_TO_DISCARD_ENTRY_IN_SECONDS;
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};
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} // namespace latinime
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#endif /* LATINIME_DYNAMIC_LANGUAGE_MODEL_PROBABILITY_UTILS_H */
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