99 lines
2.8 KiB
C++
99 lines
2.8 KiB
C++
#pragma once
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#include <cmath>
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#include "MixSegment.hpp"
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#include "IdfTrie.hpp"
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namespace cppjieba {
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using namespace limonp;
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using namespace std;
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/*utf8*/
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class KeywordExtractor {
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public:
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KeywordExtractor(const DictTrie* dictTrie,
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const HMMModel* model,
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const string& idfPath,
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const string& dat_cache_path,
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const string& stopWordPath)
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: segment_(dictTrie, model, stopWordPath),
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idf_trie_(idfPath,dat_cache_path){
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}
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~KeywordExtractor() {
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}
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void Extract(const string& sentence, vector<string>& keywords, size_t topN) const {
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vector<KeyWord> topWords;
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Extract(sentence, topWords, topN);
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for (size_t i = 0; i < topWords.size(); i++) {
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keywords.push_back(topWords[i].word);
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}
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}
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void Extract(const string& sentence, vector<pair<string, double> >& keywords, size_t topN) const {
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vector<KeyWord> topWords;
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Extract(sentence, topWords, topN);
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for (size_t i = 0; i < topWords.size(); i++) {
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keywords.push_back(pair<string, double>(topWords[i].word, topWords[i].weight));
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}
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}
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void Extract(const string& sentence, vector<KeyWord>& keywords, size_t topN) const {
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unordered_map<string, KeyWord> wordmap;//插入字符串与Word的map，相同string统计词频叠加权重
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PreFilter pre_filter(symbols_, sentence);
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RuneStrArray::const_iterator null_p;
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WordRange range(null_p, null_p);
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bool isNull(false);
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while (pre_filter.Next(range, isNull)) {
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if (isNull) {
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continue;
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}
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segment_.CutToStr(sentence, range, wordmap);
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}
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keywords.clear();
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keywords.reserve(wordmap.size());
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for (unordered_map<string, KeyWord>::iterator itr = wordmap.begin(); itr != wordmap.end(); ++itr) {
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double idf = idf_trie_.Find(itr->first);
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if (-1 != idf) {//IDF词典查找
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itr->second.weight *= idf;
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} else {
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itr->second.weight *= idf_trie_.idfAverage_;
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}
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itr->second.word = itr->first;
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keywords.push_back(itr->second);
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}
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topN = min(topN, keywords.size());
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partial_sort(keywords.begin(), keywords.begin() + topN, keywords.end(), Compare);
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keywords.resize(topN);
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}
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private:
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static bool Compare(const KeyWord& lhs, const KeyWord& rhs) {
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return lhs.weight > rhs.weight;
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}
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MixSegment segment_;
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IdfTrie idf_trie_;
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unordered_set<Rune> symbols_;
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}; // class KeywordExtractor
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inline ostream& operator << (ostream& os, const KeyWord& word) {
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return os << "{\"word\": \"" << word.word << "\", \"offset\": " << word.offsets << ", \"weight\": " << word.weight <<
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"}";
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}
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} // namespace cppjieba
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