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‎AdaBoost/template/decision_stump_adaboost.h

+22-88
Original file line numberDiff line numberDiff line change
@@ -26,28 +26,9 @@ class DecisionStumpAdaBoost : public AdaBoost {
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void init_weak_classifier();
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// learn the weak classifier
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void weak_classifier_learn(DecisionStump & stump);
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// calculate the sumation of the weights
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void calculate_weight_sum(double &weight_sum, double &weight_label_sum, double &positive_weight_sum, double &negative_weight_sum);
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// compute the outputs of the weak classifier with precalculated weights
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bool calculate_classifier_outputs(const double weight_label_sum_right,
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double &output_right,
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double &output_left,
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const double weight_sum = 0.0,
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const double weight_label_sum = 0.0,
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const double weight_sum_right = 0.0,
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const double positive_weight_sum_right = 0.0,
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const double negative_weight_sum_right = 0.0,
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const double positive_weight_sum = 0.0,
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const double negative_weight_sum = 0.0
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);
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// compute the error with precalculated weights, and the outputs of the weak classifier
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double compute_error(const double positive_weight_sum_right,
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const double negative_weight_sum_right,
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const double positive_weight_sum_left,
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const double negative_weight_sum_left,
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const double output_right,
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const double output_left
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) const;
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private:
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std::vector<DecisionStump> _weak_classifier_vec;
@@ -69,76 +50,29 @@ void DecisionStumpAdaBoost::weak_classifier_learn(DecisionStump &stump) {
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//
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}
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bool DecisionStumpAdaBoost::calculate_classifier_outputs(const double weight_label_sum_right,
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double &output_right,
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double &output_left,
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const double weight_sum,
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const double weight_label_sum,
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const double weight_sum_right,
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const double positive_weight_sum_right,
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const double negative_weight_sum_right,
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const double positive_weight_sum,
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const double negative_weight_sum
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) {
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// different boosting types, require different parameters and return different values
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switch (this->get_boosting_type()) {
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case DISCRETE_TYPE:
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if (weight_label_sum_right > 0) {
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output_right = 1.0;
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output_left = -1.0;
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} else {
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output_left = 1.0;
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output_right = -1.0;
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}
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break;
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case REAL_TYPE:
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output_right = log((positive_weight_sum_right + epsilon) / (negative_weight_sum_right + epsilon)) / 2.0;
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output_left = log((positive_weight_sum - positive_weight_sum_right + epsilon) / (negative_weight_sum - negative_weight_sum_right + epsilon)) / 2.0;
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break;
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case GENTLE_TYPE:
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output_right = weight_label_sum_right / weight_sum_right;
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output_left = (weight_label_sum - weight_label_sum_right) / (weight_sum - weight_sum_right);
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break;
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default:
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return false;
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54+
void DesisionStumpAdaboost::calculate_weight_sum(double &weight_sum, double &weight_label_sum, double &positive_weight_sum, double &negative_weight_sum) {
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weight_sum = 0.0;
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weight_label_sum = 0.0;
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positive_weight_sum = 0.0;
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negative_weight_sum = 0.0;
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size_t total_sample = this->get_total_sample();
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for (size_t i = 0; i < total_sample; ++i) {
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double w = this->get_weight_by_index(i);
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weight_sum += w;
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Record record = this->get_sorted_record_by_index(i);
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if (POSITIVE == record.label) {
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weight_label_sum += w;
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positive_weight_sum += w
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} else {
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weight_label_sum -= w;
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negative_weight_sum += w;
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}
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}
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return true;
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}
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double DecisionStumpAdaBoost::compute_error(const double positive_weight_sum_right,
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const double negative_weight_sum_right,
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const double positive_weight_sum_left,
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const double negative_weight_sum_left,
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const double output_right,
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const double output_left
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) const {
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// the error
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double error = 0.0;
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switch (this->get_boosting_type()) {
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case DISCRETE_TYPE:
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error = positive_weight_sum_right * (1.0 - output_right) / 2.0;
120-
error += positive_weight_sum_left * (1.0 - output_left) / 2.0;
121-
error += negative_weight_sum_right * (1.0 + output_right) / 2.0;
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error += negative_weight_sum_left * (1.0 + output_left) / 2.0;
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break;
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case REAL_TYPE:
125-
error = positive_weight_sum_right * exp(-output_right);
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error += positive_weight_sum_left * exp(-output_left);
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error += negative_weight_sum_right * exp(output_right);
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error += negative_weight_sum_left * exp(output_left);
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break;
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case GENTLE_TYPE:
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error = positive_weight_sum_right * (1.0 - output_right) * (1.0 - output_right);
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error += positive_weight_sum_left * (1.0 - output_left) * (1.0 - output_left);
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error += negative_weight_sum_right * (1.0 + output_right) * (1.0 + output_right);
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error += negative_weight_sum_left * (1.0 + output_left) * (1.0 + output_left);
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break;
136-
default:
137-
return error;
138-
}
139-
return error;
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}
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75+
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#endif

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