59 lines
1.6 KiB
C++
59 lines
1.6 KiB
C++
#ifndef ENGINE_MAP_MATCHING_CONFIDENCE_HPP
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#define ENGINE_MAP_MATCHING_CONFIDENCE_HPP
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#include "engine/map_matching/bayes_classifier.hpp"
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#include <cmath>
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namespace osrm
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{
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namespace engine
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{
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namespace map_matching
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{
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struct MatchingConfidence
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{
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private:
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using ClassifierT = BayesClassifier<LaplaceDistribution, LaplaceDistribution, double>;
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using TraceClassification = ClassifierT::ClassificationT;
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public:
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MatchingConfidence()
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: // the values were derived from fitting a laplace distribution
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// to the values of manually classified traces
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classifier(map_matching::LaplaceDistribution(0.005986, 0.016646),
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map_matching::LaplaceDistribution(0.054385, 0.458432),
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0.696774) // valid apriori probability
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{
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}
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double operator()(const float trace_length, const float matched_length) const
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{
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const double distance_feature = -std::log(trace_length) + std::log(matched_length);
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// matched to the same point
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if (!std::isfinite(distance_feature))
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{
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return 0;
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}
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const auto label_with_confidence = classifier.classify(distance_feature);
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if (label_with_confidence.first == ClassifierT::ClassLabel::POSITIVE)
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{
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return label_with_confidence.second;
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}
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BOOST_ASSERT(label_with_confidence.first == ClassifierT::ClassLabel::NEGATIVE);
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return 1 - label_with_confidence.second;
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}
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private:
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ClassifierT classifier;
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};
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} // namespace map_matching
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} // namespace engine
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} // namespace osrm
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#endif
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