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Merge "Add DynamicLanguageModelProbabilityUtils."

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Keisuke Kuroyanagi 2014-10-30 14:08:16 +00:00 committed by Android (Google) Code Review
parent 77947c9c96 660b00477c
commit 04a492cb49
3 changed files with 152 additions and 0 deletions
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1
native/jni/NativeFileList.mk
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@ -71,6 +71,7 @@ LATIN_IME_CORE_SRC_FILES := \
ver4_patricia_trie_writing_helper.cpp \
ver4_pt_node_array_reader.cpp) \
$(addprefix suggest/policyimpl/dictionary/structure/v4/content/, \
dynamic_language_model_probability_utils.cpp \
language_model_dict_content.cpp \
language_model_dict_content_global_counters.cpp \
shortcut_dict_content.cpp \

37
native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/dynamic_language_model_probability_utils.cpp Normal file
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@ -0,0 +1,37 @@
/*
* Copyright (C) 2014, 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.
*/
#include "suggest/policyimpl/dictionary/structure/v4/content/dynamic_language_model_probability_utils.h"
namespace latinime {
// These counts are used to provide stable probabilities even if the user's input count is small.
const int DynamicLanguageModelProbabilityUtils::ASSUMED_MIN_COUNT_FOR_UNIGRAMS = 8192;
const int DynamicLanguageModelProbabilityUtils::ASSUMED_MIN_COUNT_FOR_BIGRAMS = 2;
const int DynamicLanguageModelProbabilityUtils::ASSUMED_MIN_COUNT_FOR_TRIGRAMS = 2;
// These are encoded backoff weights.
// Note that we give positive value for trigrams that means the weight is more than 1.
// TODO: Apply backoff for main dictionaries and quit giving a positive backoff weight.
const int DynamicLanguageModelProbabilityUtils::ENCODED_BACKOFF_WEIGHT_FOR_UNIGRAMS = -32;
const int DynamicLanguageModelProbabilityUtils::ENCODED_BACKOFF_WEIGHT_FOR_BIGRAMS = 0;
const int DynamicLanguageModelProbabilityUtils::ENCODED_BACKOFF_WEIGHT_FOR_TRIGRAMS = 8;
// This value is used to remove too old entries from the dictionary.
const int DynamicLanguageModelProbabilityUtils::DURATION_TO_DISCARD_ENTRY_IN_SECONDS =
300 * 24 * 60 * 60; // 300 days
} // namespace latinime

114
native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/dynamic_language_model_probability_utils.h Normal file
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@ -0,0 +1,114 @@
/*
* Copyright (C) 2014, 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_DYNAMIC_LANGUAGE_MODEL_PROBABILITY_UTILS_H
#define LATINIME_DYNAMIC_LANGUAGE_MODEL_PROBABILITY_UTILS_H
#include <algorithm>
#include "defines.h"
#include "suggest/core/dictionary/property/historical_info.h"
#include "utils/time_keeper.h"
namespace latinime {
class DynamicLanguageModelProbabilityUtils {
public:
static float computeRawProbabilityFromCounts(const int count, const int contextCount,
const int matchedWordCountInContext) {
int minCount = 0;
switch (matchedWordCountInContext) {
case 1:
minCount = ASSUMED_MIN_COUNT_FOR_UNIGRAMS;
break;
case 2:
minCount = ASSUMED_MIN_COUNT_FOR_BIGRAMS;
break;
case 3:
minCount = ASSUMED_MIN_COUNT_FOR_TRIGRAMS;
break;
default:
AKLOGE("computeRawProbabilityFromCounts is called with invalid "
"matchedWordCountInContext (%d).", matchedWordCountInContext);
ASSERT(false);
return 0.0f;
}
return static_cast<float>(count) / static_cast<float>(std::max(contextCount, minCount));
}
static float backoff(const int ngramProbability, const int matchedWordCountInContext) {
int probability = NOT_A_PROBABILITY;
switch (matchedWordCountInContext) {
case 1:
probability = ngramProbability + ENCODED_BACKOFF_WEIGHT_FOR_UNIGRAMS;
break;
case 2:
probability = ngramProbability + ENCODED_BACKOFF_WEIGHT_FOR_BIGRAMS;
break;
case 3:
probability = ngramProbability + ENCODED_BACKOFF_WEIGHT_FOR_TRIGRAMS;
break;
default:
AKLOGE("backoff is called with invalid matchedWordCountInContext (%d).",
matchedWordCountInContext);
ASSERT(false);
return NOT_A_PROBABILITY;
}
return std::min(std::max(probability, NOT_A_PROBABILITY), MAX_PROBABILITY);
}
static int getDecayedProbability(const int probability, const HistoricalInfo historicalInfo) {
const int elapsedTime = TimeKeeper::peekCurrentTime() - historicalInfo.getTimestamp();
if (elapsedTime < 0) {
AKLOGE("The elapsed time is negatime value. Timestamp overflow?");
return NOT_A_PROBABILITY;
}
// TODO: Improve this logic.
// We don't modify probability depending on the elapsed time.
return probability;
}
static int shouldRemoveEntryDuringGC(const HistoricalInfo historicalInfo) {
// TODO: Improve this logic.
const int elapsedTime = TimeKeeper::peekCurrentTime() - historicalInfo.getTimestamp();
return elapsedTime > DURATION_TO_DISCARD_ENTRY_IN_SECONDS;
}
static int getPriorityToPreventFromEviction(const HistoricalInfo historicalInfo) {
// TODO: Improve this logic.
// More recently input entries get higher priority.
return historicalInfo.getTimestamp();
}
private:
DISALLOW_IMPLICIT_CONSTRUCTORS(DynamicLanguageModelProbabilityUtils);
static_assert(MAX_PREV_WORD_COUNT_FOR_N_GRAM <= 2, "Max supported Ngram is Trigram.");
static const int ASSUMED_MIN_COUNT_FOR_UNIGRAMS;
static const int ASSUMED_MIN_COUNT_FOR_BIGRAMS;
static const int ASSUMED_MIN_COUNT_FOR_TRIGRAMS;
static const int ENCODED_BACKOFF_WEIGHT_FOR_UNIGRAMS;
static const int ENCODED_BACKOFF_WEIGHT_FOR_BIGRAMS;
static const int ENCODED_BACKOFF_WEIGHT_FOR_TRIGRAMS;
static const int DURATION_TO_DISCARD_ENTRY_IN_SECONDS;
};
} // namespace latinime
#endif /* LATINIME_DYNAMIC_LANGUAGE_MODEL_PROBABILITY_UTILS_H */