void
PerceptronModel::ComputeFeaturesToUpdate(const CandidateSet &example,
unordered_set<int> &
gold_features_to_update,
unordered_set<int> &
best_scoring_features_to_update)
const {
// Collect gold features that are not in best-scoring candidate.
const FeatureVector<int,double> &gold_features =
example.GetGold().features();
const FeatureVector<int,double> &best_scoring_features =
example.GetBestScoring().features();
if (DEBUG >= 2) {
cerr << "Gold index: " << example.gold_index()
<< "; best scoring index: " << example.best_scoring_index()
<< endl;
cerr << "Original gold features: " << gold_features << endl
<< "Original best scoring features: " << best_scoring_features << endl;
}
gold_features.GetNonZeroFeatures(gold_features_to_update);
best_scoring_features.RemoveEqualFeatures(gold_features,
gold_features_to_update);
if (DEBUG >= 2) {
cerr << "Time:" << time_.to_string() << ": new gold features: [";
for (unordered_set<int>::const_iterator it =
gold_features_to_update.begin();
it != gold_features_to_update.end();
++it) {
cerr << " " << *it;
}
cerr << "]" << endl;
}
best_scoring_features.GetNonZeroFeatures(best_scoring_features_to_update);
gold_features.RemoveEqualFeatures(best_scoring_features,
best_scoring_features_to_update);
if (DEBUG >= 2) {
cerr << "Time:" << time_.to_string() << ": new best scoring features: [";
for (unordered_set<int>::const_iterator it =
best_scoring_features_to_update.begin();
it != best_scoring_features_to_update.end();
++it) {
cerr << " " << *it;
}
cerr << "]" << endl;
}
}
void
PerceptronModel::TrainOnExample(CandidateSet &example) {
time_.Tick();
if (symbols_ != NULL) {
example.CompileFeatures(symbols_);
}
bool training = true;
ScoreCandidates(example, training);
if (NeedToUpdate(example)) {
if (DEBUG >= 2) {
cerr << "Time:" << time_.to_string() << ": need to update because "
<< "best scoring index " << example.best_scoring_index()
<< " is not equal to gold index " << example.gold_index() << endl;
}
++(*num_training_errors_per_epoch_.rbegin());
++num_training_errors_;
Update(example);
}
}
bool
PerceptronModel::DefaultUpdatePredicate::NeedToUpdate(Model *model,
CandidateSet &example) {
return example.best_scoring_index() != example.gold_index();
}
