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https://github.com/moses-smt/mosesdecoder.git
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90 lines
2.5 KiB
C++
90 lines
2.5 KiB
C++
#ifndef MERT_REFERENCE_H_
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#define MERT_REFERENCE_H_
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#include <algorithm>
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#include <climits>
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#include <vector>
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#include "Ngram.h"
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namespace MosesTuning
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{
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/**
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* Reference class represents reference translations for an output
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* translation used in calculating BLEU score.
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*/
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class Reference {
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public:
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// for m_length
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typedef std::vector<std::size_t>::iterator iterator;
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typedef std::vector<std::size_t>::const_iterator const_iterator;
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Reference() : m_counts(new NgramCounts) { }
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~Reference() { delete m_counts; }
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NgramCounts* get_counts() { return m_counts; }
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const NgramCounts* get_counts() const { return m_counts; }
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iterator begin() { return m_length.begin(); }
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const_iterator begin() const { return m_length.begin(); }
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iterator end() { return m_length.end(); }
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const_iterator end() const { return m_length.end(); }
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void push_back(std::size_t len) { m_length.push_back(len); }
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std::size_t num_references() const { return m_length.size(); }
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int CalcAverage() const;
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int CalcClosest(std::size_t length) const;
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int CalcShortest() const;
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private:
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NgramCounts* m_counts;
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// multiple reference lengths
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std::vector<std::size_t> m_length;
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};
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// TODO(tetsuok): fix this function and related stuff.
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// "average" reference length should not be calculated at sentence-level unlike "closest".
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inline int Reference::CalcAverage() const {
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int total = 0;
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for (std::size_t i = 0; i < m_length.size(); ++i) {
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total += m_length[i];
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}
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return static_cast<int>(
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static_cast<float>(total) / m_length.size());
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}
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inline int Reference::CalcClosest(std::size_t length) const {
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int min_diff = INT_MAX;
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int closest_ref_id = 0; // an index of the closest reference translation
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for (std::size_t i = 0; i < m_length.size(); ++i) {
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const int ref_length = m_length[i];
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const int length_diff = abs(ref_length - static_cast<int>(length));
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const int abs_min_diff = abs(min_diff);
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// Look for the closest reference
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if (length_diff < abs_min_diff) {
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min_diff = ref_length - length;
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closest_ref_id = i;
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// if two references has the same closest length, take the shortest
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} else if (length_diff == abs_min_diff) {
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if (ref_length < static_cast<int>(m_length[closest_ref_id])) {
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closest_ref_id = i;
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}
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}
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}
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return static_cast<int>(m_length[closest_ref_id]);
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}
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inline int Reference::CalcShortest() const {
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return *std::min_element(m_length.begin(), m_length.end());
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}
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}
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#endif // MERT_REFERENCE_H_
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