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https://github.com/moses-smt/mosesdecoder.git
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154 lines
4.9 KiB
C++
154 lines
4.9 KiB
C++
/*
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* LatticeMBR.h
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* moses-cmd
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*
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* Created by Abhishek Arun on 26/01/2010.
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* Copyright 2010 __MyCompanyName__. All rights reserved.
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*
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*/
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#ifndef moses_cmd_LatticeMBR_h
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#define moses_cmd_LatticeMBR_h
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#include <map>
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#include <vector>
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#include <set>
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#include "moses/Hypothesis.h"
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#include "moses/Manager.h"
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#include "moses/TrellisPathList.h"
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namespace Moses
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{
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class Edge;
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typedef std::vector< const Moses::Hypothesis *> Lattice;
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typedef std::vector<const Edge*> Path;
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typedef std::map<Path, size_t> PathCounts;
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typedef std::map<Moses::Phrase, PathCounts > NgramHistory;
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class Edge
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{
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const Moses::Hypothesis* m_tailNode;
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const Moses::Hypothesis* m_headNode;
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float m_score;
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Moses::TargetPhrase m_targetPhrase;
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NgramHistory m_ngrams;
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public:
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Edge(const Moses::Hypothesis* from, const Moses::Hypothesis* to, float score, const Moses::TargetPhrase& targetPhrase) : m_tailNode(from), m_headNode(to), m_score(score), m_targetPhrase(targetPhrase) {
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//cout << "Creating new edge from Node " << from->GetId() << ", to Node : " << to->GetId() << ", score: " << score << " phrase: " << targetPhrase << endl;
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}
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const Moses::Hypothesis* GetHeadNode() const {
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return m_headNode;
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}
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const Moses::Hypothesis* GetTailNode() const {
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return m_tailNode;
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}
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float GetScore() const {
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return m_score;
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}
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size_t GetWordsSize() const {
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return m_targetPhrase.GetSize();
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}
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const Moses::Phrase& GetWords() const {
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return m_targetPhrase;
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}
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friend std::ostream& operator<< (std::ostream& out, const Edge& edge);
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const NgramHistory& GetNgrams( std::map<const Moses::Hypothesis*, std::vector<Edge> > & incomingEdges) ;
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bool operator < (const Edge & compare) const;
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void GetPhraseSuffix(const Moses::Phrase& origPhrase, size_t lastN, Moses::Phrase& targetPhrase) const;
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void storeNgramHistory(const Moses::Phrase& phrase, Path & path, size_t count = 1) {
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m_ngrams[phrase][path]+= count;
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}
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};
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/**
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* Data structure to hold the ngram scores as we traverse the lattice. Maps (hypo,ngram) to score
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*/
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class NgramScores
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{
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public:
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NgramScores() {}
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/** logsum this score to the existing score */
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void addScore(const Moses::Hypothesis* node, const Moses::Phrase& ngram, float score);
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/** Iterate through ngrams for selected node */
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typedef std::map<const Moses::Phrase*, float>::const_iterator NodeScoreIterator;
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NodeScoreIterator nodeBegin(const Moses::Hypothesis* node);
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NodeScoreIterator nodeEnd(const Moses::Hypothesis* node);
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private:
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std::set<Moses::Phrase> m_ngrams;
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std::map<const Moses::Hypothesis*, std::map<const Moses::Phrase*, float> > m_scores;
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};
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/** Holds a lattice mbr solution, and its scores */
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class LatticeMBRSolution
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{
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public:
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/** Read the words from the path */
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LatticeMBRSolution(const Moses::TrellisPath& path, bool isMap);
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const std::vector<float>& GetNgramScores() const {
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return m_ngramScores;
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}
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const std::vector<Moses::Word>& GetWords() const {
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return m_words;
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}
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float GetMapScore() const {
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return m_mapScore;
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}
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float GetScore() const {
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return m_score;
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}
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/** Initialise ngram scores */
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void CalcScore(std::map<Moses::Phrase, float>& finalNgramScores, const std::vector<float>& thetas, float mapWeight);
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private:
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std::vector<Moses::Word> m_words;
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float m_mapScore;
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std::vector<float> m_ngramScores;
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float m_score;
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};
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struct LatticeMBRSolutionComparator {
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bool operator()(const LatticeMBRSolution& a, const LatticeMBRSolution& b) {
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return a.GetScore() > b.GetScore();
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}
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};
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void pruneLatticeFB(Lattice & connectedHyp, std::map < const Moses::Hypothesis*, std::set <const Moses::Hypothesis* > > & outgoingHyps, std::map<const Moses::Hypothesis*, std::vector<Edge> >& incomingEdges,
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const std::vector< float> & estimatedScores, const Moses::Hypothesis*, size_t edgeDensity,float scale);
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//Use the ngram scores to rerank the nbest list, return at most n solutions
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void getLatticeMBRNBest(const Moses::Manager& manager, const Moses::TrellisPathList& nBestList, std::vector<LatticeMBRSolution>& solutions, size_t n);
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//calculate expectated ngram counts, clipping at 1 (ie calculating posteriors) if posteriors==true.
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void calcNgramExpectations(Lattice & connectedHyp, std::map<const Moses::Hypothesis*, std::vector<Edge> >& incomingEdges, std::map<Moses::Phrase,
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float>& finalNgramScores, bool posteriors);
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void GetOutputFactors(const Moses::TrellisPath &path, std::vector <Moses::Word> &translation);
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void extract_ngrams(const std::vector<Moses::Word >& sentence, std::map < Moses::Phrase, int > & allngrams);
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bool ascendingCoverageCmp(const Moses::Hypothesis* a, const Moses::Hypothesis* b);
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std::vector<Moses::Word> doLatticeMBR(const Moses::Manager& manager, const Moses::TrellisPathList& nBestList);
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const Moses::TrellisPath doConsensusDecoding(const Moses::Manager& manager, const Moses::TrellisPathList& nBestList);
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//std::vector<Moses::Word> doConsensusDecoding(Moses::Manager& manager, Moses::TrellisPathList& nBestList);
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}
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#endif
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