#include "scorer.h" #include <map> #include <sstream> #include <iostream> #include <fstream> #include <cstdio> #include <valarray> #include <boost/shared_ptr.hpp> #include "viterbi_envelope.h" #include "error_surface.h" #include "ter.h" #include "comb_scorer.h" #include "tdict.h" #include "stringlib.h" using boost::shared_ptr; using namespace std; const bool minimize_segments = true; // if adjacent segments have equal scores, merge them ScoreType ScoreTypeFromString(const std::string& st) { const string sl = LowercaseString(st); if (sl == "ser") return SER; if (sl == "ter") return TER; if (sl == "bleu" || sl == "ibm_bleu") return IBM_BLEU; if (sl == "nist_bleu") return NIST_BLEU; if (sl == "koehn_bleu") return Koehn_BLEU; if (sl == "combi") return BLEU_minus_TER_over_2; cerr << "Don't understand score type '" << sl << "', defaulting to ibm_bleu.\n"; return IBM_BLEU; } Score::~Score() {} SentenceScorer::~SentenceScorer() {} class SERScore : public Score { friend class SERScorer; public: SERScore() : correct(0), total(0) {} float ComputeScore() const { return static_cast<float>(correct) / static_cast<float>(total); } void ScoreDetails(string* details) const { ostringstream os; os << "SER= " << ComputeScore() << " (" << correct << '/' << total << ')'; *details = os.str(); } void PlusEquals(const Score& delta) { correct += static_cast<const SERScore&>(delta).correct; total += static_cast<const SERScore&>(delta).total; } Score* GetZero() const { return new SERScore; } void Subtract(const Score& rhs, Score* res) const { SERScore* r = static_cast<SERScore*>(res); r->correct = correct - static_cast<const SERScore&>(rhs).correct; r->total = total - static_cast<const SERScore&>(rhs).total; } void Encode(std::string* out) const { assert(!"not implemented"); } bool IsAdditiveIdentity() const { return (total == 0 && correct == 0); // correct is always 0 <= n <= total } private: int correct, total; }; class SERScorer : public SentenceScorer { public: SERScorer(const vector<vector<WordID> >& references) : refs_(references) {} Score* ScoreCandidate(const std::vector<WordID>& hyp) const { SERScore* res = new SERScore; res->total = 1; for (int i = 0; i < refs_.size(); ++i) if (refs_[i] == hyp) res->correct = 1; return res; } static Score* ScoreFromString(const std::string& data) { assert(!"Not implemented"); } private: vector<vector<WordID> > refs_; }; class BLEUScore : public Score { friend class BLEUScorerBase; public: BLEUScore(int n) : correct_ngram_hit_counts(0,n), hyp_ngram_counts(0,n) { ref_len = 0; hyp_len = 0; } float ComputeScore() const; void ScoreDetails(string* details) const; void PlusEquals(const Score& delta); Score* GetZero() const; void Subtract(const Score& rhs, Score* res) const; void Encode(std::string* out) const; bool IsAdditiveIdentity() const { if (fabs(ref_len) > 0.1f || hyp_len != 0) return false; for (int i = 0; i < correct_ngram_hit_counts.size(); ++i) if (hyp_ngram_counts[i] != 0 || correct_ngram_hit_counts[i] != 0) return false; return true; } private: float ComputeScore(vector<float>* precs, float* bp) const; valarray<int> correct_ngram_hit_counts; valarray<int> hyp_ngram_counts; float ref_len; int hyp_len; }; class BLEUScorerBase : public SentenceScorer { public: BLEUScorerBase(const std::vector<std::vector<WordID> >& references, int n ); Score* ScoreCandidate(const std::vector<WordID>& hyp) const; static Score* ScoreFromString(const std::string& in); protected: virtual float ComputeRefLength(const vector<WordID>& hyp) const = 0; private: struct NGramCompare { int operator() (const vector<WordID>& a, const vector<WordID>& b) { size_t as = a.size(); size_t bs = b.size(); const size_t s = (as < bs ? as : bs); for (size_t i = 0; i < s; ++i) { int d = a[i] - b[i]; if (d < 0) return true; if (d > 0) return false; } return as < bs; } }; typedef map<vector<WordID>, pair<int,int>, NGramCompare> NGramCountMap; void CountRef(const vector<WordID>& ref) { NGramCountMap tc; vector<WordID> ngram(n_); int s = ref.size(); for (int j=0; j<s; ++j) { int remaining = s-j; int k = (n_ < remaining ? n_ : remaining); ngram.clear(); for (int i=1; i<=k; ++i) { ngram.push_back(ref[j + i - 1]); tc[ngram].first++; } } for (NGramCountMap::iterator i = tc.begin(); i != tc.end(); ++i) { pair<int,int>& p = ngrams_[i->first]; if (p.first < i->second.first) p = i->second; } } void ComputeNgramStats(const vector<WordID>& sent, valarray<int>* correct, valarray<int>* hyp) const { assert(correct->size() == n_); assert(hyp->size() == n_); vector<WordID> ngram(n_); (*correct) *= 0; (*hyp) *= 0; int s = sent.size(); for (int j=0; j<s; ++j) { int remaining = s-j; int k = (n_ < remaining ? n_ : remaining); ngram.clear(); for (int i=1; i<=k; ++i) { ngram.push_back(sent[j + i - 1]); pair<int,int>& p = ngrams_[ngram]; if (p.second < p.first) { ++p.second; (*correct)[i-1]++; } // if the 1 gram isn't found, don't try to match don't need to match any 2- 3- .. grams: if (!p.first) { for (; i<=k; ++i) (*hyp)[i-1]++; } else { (*hyp)[i-1]++; } } } } mutable NGramCountMap ngrams_; int n_; vector<int> lengths_; }; Score* BLEUScorerBase::ScoreFromString(const std::string& in) { istringstream is(in); int n; is >> n; BLEUScore* r = new BLEUScore(n); is >> r->ref_len >> r->hyp_len; for (int i = 0; i < n; ++i) { is >> r->correct_ngram_hit_counts[i]; is >> r->hyp_ngram_counts[i]; } return r; } class IBM_BLEUScorer : public BLEUScorerBase { public: IBM_BLEUScorer(const std::vector<std::vector<WordID> >& references, int n=4) : BLEUScorerBase(references, n), lengths_(references.size()) { for (int i=0; i < references.size(); ++i) lengths_[i] = references[i].size(); } protected: float ComputeRefLength(const vector<WordID>& hyp) const { if (lengths_.size() == 1) return lengths_[0]; int bestd = 2000000; int hl = hyp.size(); int bl = -1; for (vector<int>::const_iterator ci = lengths_.begin(); ci != lengths_.end(); ++ci) { int cl = *ci; if (abs(cl - hl) < bestd) { bestd = abs(cl - hl); bl = cl; } } return bl; } private: vector<int> lengths_; }; class NIST_BLEUScorer : public BLEUScorerBase { public: NIST_BLEUScorer(const std::vector<std::vector<WordID> >& references, int n=4) : BLEUScorerBase(references, n), shortest_(references[0].size()) { for (int i=1; i < references.size(); ++i) if (references[i].size() < shortest_) shortest_ = references[i].size(); } protected: float ComputeRefLength(const vector<WordID>& hyp) const { return shortest_; } private: float shortest_; }; class Koehn_BLEUScorer : public BLEUScorerBase { public: Koehn_BLEUScorer(const std::vector<std::vector<WordID> >& references, int n=4) : BLEUScorerBase(references, n), avg_(0) { for (int i=0; i < references.size(); ++i) avg_ += references[i].size(); avg_ /= references.size(); } protected: float ComputeRefLength(const vector<WordID>& hyp) const { return avg_; } private: float avg_; }; SentenceScorer* SentenceScorer::CreateSentenceScorer(const ScoreType type, const std::vector<std::vector<WordID> >& refs) { switch (type) { case IBM_BLEU: return new IBM_BLEUScorer(refs, 4); case NIST_BLEU: return new NIST_BLEUScorer(refs, 4); case Koehn_BLEU: return new Koehn_BLEUScorer(refs, 4); case TER: return new TERScorer(refs); case SER: return new SERScorer(refs); case BLEU_minus_TER_over_2: return new BLEUTERCombinationScorer(refs); default: assert(!"Not implemented!"); } } Score* SentenceScorer::CreateScoreFromString(const ScoreType type, const std::string& in) { switch (type) { case IBM_BLEU: case NIST_BLEU: case Koehn_BLEU: return BLEUScorerBase::ScoreFromString(in); case TER: return TERScorer::ScoreFromString(in); case SER: return SERScorer::ScoreFromString(in); case BLEU_minus_TER_over_2: return BLEUTERCombinationScorer::ScoreFromString(in); default: assert(!"Not implemented!"); } } void SentenceScorer::ComputeErrorSurface(const ViterbiEnvelope& ve, ErrorSurface* env) const { vector<WordID> prev_trans; const vector<shared_ptr<Segment> >& ienv = ve.GetSortedSegs(); env->resize(ienv.size()); Score* prev_score = NULL; int j = 0; for (int i = 0; i < ienv.size(); ++i) { const Segment& seg = *ienv[i]; vector<WordID> trans; seg.ConstructTranslation(&trans); // cerr << "Scoring: " << TD::GetString(trans) << endl; if (trans == prev_trans) { if (!minimize_segments) { assert(prev_score); // if this fails, it means // the decoder can generate null translations ErrorSegment& out = (*env)[j]; out.delta = prev_score->GetZero(); out.x = seg.x; ++j; } // cerr << "Identical translation, skipping scoring\n"; } else { Score* score = ScoreCandidate(trans); // cerr << "score= " << score->ComputeScore() << "\n"; Score* cur_delta = score->GetZero(); // just record the score diffs if (!prev_score) prev_score = score->GetZero(); score->Subtract(*prev_score, cur_delta); delete prev_score; prev_trans.swap(trans); prev_score = score; if ((!minimize_segments) || (!cur_delta->IsAdditiveIdentity())) { ErrorSegment& out = (*env)[j]; out.delta = cur_delta; out.x = seg.x; ++j; } } } delete prev_score; // cerr << " In segments: " << ienv.size() << endl; // cerr << "Out segments: " << j << endl; assert(j > 0); env->resize(j); } void BLEUScore::ScoreDetails(std::string* details) const { char buf[2000]; vector<float> precs(4); float bp; float bleu = ComputeScore(&precs, &bp); sprintf(buf, "BLEU = %.2f, %.1f|%.1f|%.1f|%.1f (brev=%.3f)", bleu*100.0, precs[0]*100.0, precs[1]*100.0, precs[2]*100.0, precs[3]*100.0, bp); *details = buf; } float BLEUScore::ComputeScore(vector<float>* precs, float* bp) const { float log_bleu = 0; if (precs) precs->clear(); int count = 0; for (int i = 0; i < hyp_ngram_counts.size(); ++i) { if (hyp_ngram_counts[i] > 0) { float lprec = log(correct_ngram_hit_counts[i]) - log(hyp_ngram_counts[i]); if (precs) precs->push_back(exp(lprec)); log_bleu += lprec; ++count; } } log_bleu /= static_cast<float>(count); float lbp = 0.0; if (hyp_len < ref_len) lbp = (hyp_len - ref_len) / hyp_len; log_bleu += lbp; if (bp) *bp = exp(lbp); return exp(log_bleu); } float BLEUScore::ComputeScore() const { return ComputeScore(NULL, NULL); } void BLEUScore::Subtract(const Score& rhs, Score* res) const { const BLEUScore& d = static_cast<const BLEUScore&>(rhs); BLEUScore* o = static_cast<BLEUScore*>(res); o->ref_len = ref_len - d.ref_len; o->hyp_len = hyp_len - d.hyp_len; o->correct_ngram_hit_counts = correct_ngram_hit_counts - d.correct_ngram_hit_counts; o->hyp_ngram_counts = hyp_ngram_counts - d.hyp_ngram_counts; } void BLEUScore::PlusEquals(const Score& delta) { const BLEUScore& d = static_cast<const BLEUScore&>(delta); correct_ngram_hit_counts += d.correct_ngram_hit_counts; hyp_ngram_counts += d.hyp_ngram_counts; ref_len += d.ref_len; hyp_len += d.hyp_len; } Score* BLEUScore::GetZero() const { return new BLEUScore(hyp_ngram_counts.size()); } void BLEUScore::Encode(std::string* out) const { ostringstream os; const int n = correct_ngram_hit_counts.size(); os << n << ' ' << ref_len << ' ' << hyp_len; for (int i = 0; i < n; ++i) os << ' ' << correct_ngram_hit_counts[i] << ' ' << hyp_ngram_counts[i]; *out = os.str(); } BLEUScorerBase::BLEUScorerBase(const std::vector<std::vector<WordID> >& references, int n) : n_(n) { for (vector<vector<WordID> >::const_iterator ci = references.begin(); ci != references.end(); ++ci) { lengths_.push_back(ci->size()); CountRef(*ci); } } Score* BLEUScorerBase::ScoreCandidate(const vector<WordID>& hyp) const { BLEUScore* bs = new BLEUScore(n_); for (NGramCountMap::iterator i=ngrams_.begin(); i != ngrams_.end(); ++i) i->second.second = 0; ComputeNgramStats(hyp, &bs->correct_ngram_hit_counts, &bs->hyp_ngram_counts); bs->ref_len = ComputeRefLength(hyp); bs->hyp_len = hyp.size(); return bs; } DocScorer::~DocScorer() { for (int i=0; i < scorers_.size(); ++i) delete scorers_[i]; } DocScorer::DocScorer( const ScoreType type, const std::vector<std::string>& ref_files) { // TODO stop using valarray, start using ReadFile cerr << "Loading references (" << ref_files.size() << " files)\n"; valarray<ifstream> ifs(ref_files.size()); for (int i=0; i < ref_files.size(); ++i) { ifs[i].open(ref_files[i].c_str()); assert(ifs[i].good()); } char buf[64000]; bool expect_eof = false; while (!ifs[0].eof()) { vector<vector<WordID> > refs(ref_files.size()); for (int i=0; i < ref_files.size(); ++i) { if (ifs[i].eof()) break; ifs[i].getline(buf, 64000); refs[i].clear(); if (strlen(buf) == 0) { if (ifs[i].eof()) { if (!expect_eof) { assert(i == 0); expect_eof = true; } break; } } else { TD::ConvertSentence(buf, &refs[i]); assert(!refs[i].empty()); } assert(!expect_eof); } if (!expect_eof) scorers_.push_back(SentenceScorer::CreateSentenceScorer(type, refs)); } cerr << "Loaded reference translations for " << scorers_.size() << " sentences.\n"; }