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/*
* LatticeMBR.h
* moses-cmd
*
* Created by Abhishek Arun on 26/01/2010.
* Copyright 2010 __MyCompanyName__. All rights reserved.
*
*/
#ifndef moses_cmd_LatticeMBR_h
#define moses_cmd_LatticeMBR_h
#include <map>
#include <vector>
#include <set>
#include "Hypothesis.h"
#include "Manager.h"
#include "TrellisPathList.h"
using namespace Moses;
template<class T>
T log_sum (T log_a, T log_b)
{
T v;
if (log_a < log_b) {
v = log_b+log ( 1 + exp ( log_a-log_b ));
} else {
v = log_a+log ( 1 + exp ( log_b-log_a ));
}
return ( v );
}
class Edge;
typedef std::vector< const Hypothesis *> Lattice;
typedef vector<const Edge*> Path;
typedef map<Path, size_t> PathCounts;
typedef map<Phrase, PathCounts > NgramHistory;
class Edge {
const Hypothesis* m_tailNode;
const Hypothesis* m_headNode;
float m_score;
TargetPhrase m_targetPhrase;
NgramHistory m_ngrams;
public:
Edge(const Hypothesis* from, const Hypothesis* to, float score, const TargetPhrase& targetPhrase) : m_tailNode(from), m_headNode(to), m_score(score), m_targetPhrase(targetPhrase) {
//cout << "Creating new edge from Node " << from->GetId() << ", to Node : " << to->GetId() << ", score: " << score << " phrase: " << targetPhrase << endl;
}
const Hypothesis* GetHeadNode() const {
return m_headNode;
}
const Hypothesis* GetTailNode() const {
return m_tailNode;
}
float GetScore() const {
return m_score;
}
size_t GetWordsSize() const {
return m_targetPhrase.GetSize();
}
const Phrase& GetWords() const {
return m_targetPhrase;
}
friend ostream& operator<< (ostream& out, const Edge& edge);
const NgramHistory& GetNgrams( map<const Hypothesis*, vector<Edge> > & incomingEdges) ;
bool operator < (const Edge & compare) const;
void GetPhraseSuffix(const Phrase& origPhrase, size_t lastN, Phrase& targetPhrase) const;
void storeNgramHistory(const Phrase& phrase, Path & path, size_t count = 1){
m_ngrams[phrase][path]+= count;
}
};
/**
* Data structure to hold the ngram scores as we traverse the lattice. Maps (hypo,ngram) to score
*/
class NgramScores {
public:
NgramScores() {}
/** logsum this score to the existing score */
void addScore(const Hypothesis* node, const Phrase& ngram, float score);
/** Iterate through ngrams for selected node */
typedef map<const Phrase*, float>::const_iterator NodeScoreIterator;
NodeScoreIterator nodeBegin(const Hypothesis* node);
NodeScoreIterator nodeEnd(const Hypothesis* node);
private:
set<Phrase> m_ngrams;
map<const Hypothesis*, map<const Phrase*, float> > m_scores;
};
void pruneLatticeFB(Lattice & connectedHyp, map < const Hypothesis*, set <const Hypothesis* > > & outgoingHyps, map<const Hypothesis*, vector<Edge> >& incomingEdges,
const vector< float> & estimatedScores, const Hypothesis*, size_t edgeDensity);
vector<Word> calcMBRSol(Lattice & connectedHyp, map<Phrase, float>& finalNgramScores,const vector<float> & thetas, float, float);
vector<Word> calcMBRSol(const TrellisPathList& nBestList, map<Phrase, float>& finalNgramScores,const vector<float> & thetas, float, float);
void calcNgramPosteriors(Lattice & connectedHyp, map<const Hypothesis*, vector<Edge> >& incomingEdges, float scale, map<Phrase, float>& finalNgramScores);
void GetOutputFactors(const TrellisPath &path, vector <Word> &translation);
void extract_ngrams(const vector<Word >& sentence, map < Phrase, int > & allngrams);
bool ascendingCoverageCmp(const Hypothesis* a, const Hypothesis* b);
vector<Word> doLatticeMBR(Manager& manager, TrellisPathList& nBestList);
#endif
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