diff options
Diffstat (limited to 'dtrain/score.cc')
| -rw-r--r-- | dtrain/score.cc | 62 |
1 files changed, 58 insertions, 4 deletions
diff --git a/dtrain/score.cc b/dtrain/score.cc index 5bb0bcaa..4a7cac6e 100644 --- a/dtrain/score.cc +++ b/dtrain/score.cc @@ -80,7 +80,7 @@ StupidBleuScorer::Score(vector<WordID>& hyp, vector<WordID>& ref, * to Machine Translation" * (Liang et al. '06) * - * NOTE: max is 0.9375 + * NOTE: max is 0.9375 (with N=4) */ score_t SmoothBleuScorer::Score(vector<WordID>& hyp, vector<WordID>& ref, @@ -108,9 +108,13 @@ SmoothBleuScorer::Score(vector<WordID>& hyp, vector<WordID>& ref, return brevity_penalty(hyp_len, ref_len) * sum; } -// variant of smooth_bleu; i-Bleu scores only single 'i' +/* + * 'sum' bleu + * + * sum up Ngram precisions + */ score_t -SmoothSingleBleuScorer::Score(vector<WordID>& hyp, vector<WordID>& ref, +SumBleuScorer::Score(vector<WordID>& hyp, vector<WordID>& ref, const unsigned /*rank*/, const unsigned /*src_len*/) { unsigned hyp_len = hyp.size(), ref_len = ref.size(); @@ -128,7 +132,57 @@ SmoothSingleBleuScorer::Score(vector<WordID>& hyp, vector<WordID>& ref, return brevity_penalty(hyp_len, ref_len) * sum; } -// TODO single variants! +/* + * 'sum' (exp) bleu + * + * sum up exp(Ngram precisions) + */ +score_t +SumExpBleuScorer::Score(vector<WordID>& hyp, vector<WordID>& ref, + const unsigned /*rank*/, const unsigned /*src_len*/) +{ + unsigned hyp_len = hyp.size(), ref_len = ref.size(); + if (hyp_len == 0 || ref_len == 0) return 0.; + NgramCounts counts = make_ngram_counts(hyp, ref, N_); + unsigned M = N_; + if (ref_len < N_) M = ref_len; + score_t sum = 0.; + unsigned j = 1; + for (unsigned i = 0; i < M; i++) { + if (counts.sum_[i] == 0 || counts.clipped_[i] == 0) break; + sum += exp(((score_t)counts.clipped_[i]/counts.sum_[i]))/pow(2., N_-j+1); + j++; + } + return brevity_penalty(hyp_len, ref_len) * sum; +} + +/* + * 'sum' (whatever) bleu + * + * sum up exp(weight * log(Ngram precisions)) + */ +score_t +SumWhateverBleuScorer::Score(vector<WordID>& hyp, vector<WordID>& ref, + const unsigned /*rank*/, const unsigned /*src_len*/) +{ + unsigned hyp_len = hyp.size(), ref_len = ref.size(); + if (hyp_len == 0 || ref_len == 0) return 0.; + NgramCounts counts = make_ngram_counts(hyp, ref, N_); + unsigned M = N_; + vector<score_t> v = w_; + if (ref_len < N_) { + M = ref_len; + for (unsigned i = 0; i < M; i++) v[i] = 1/((score_t)M); + } + score_t sum = 0.; + unsigned j = 1; + for (unsigned i = 0; i < M; i++) { + if (counts.sum_[i] == 0 || counts.clipped_[i] == 0) break; + sum += exp(v[i] * log(((score_t)counts.clipped_[i]/counts.sum_[i])))/pow(2., N_-j+1); + j++; + } + return brevity_penalty(hyp_len, ref_len) * sum; +} /* * approx. bleu |