You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
72 lines
1.8 KiB
72 lines
1.8 KiB
6 years ago
|
#pragma once
|
||
|
|
|
||
|
|
class SplitEvaluator {
|
||
|
|
public:
|
||
|
|
SplitEvaluator(bool normalize)
|
||
|
|
: normalize_(normalize) {}
|
||
|
|
|
||
|
|
virtual ~SplitEvaluator() {}
|
||
|
|
|
||
|
|
virtual float Eval(const std::vector<TrainDatum>& lefttargets, const std::vector<TrainDatum>& righttargets, int depth) const {
|
||
|
|
float purity_left = Purity(lefttargets, depth);
|
||
|
|
float purity_right = Purity(righttargets, depth);
|
||
|
|
|
||
|
|
float normalize_left = 1.0;
|
||
|
|
float normalize_right = 1.0;
|
||
|
|
|
||
|
|
if(normalize_) {
|
||
|
|
unsigned int n_left = lefttargets.size();
|
||
|
|
unsigned int n_right = righttargets.size();
|
||
|
|
unsigned int n_total = n_left + n_right;
|
||
|
|
|
||
|
|
normalize_left = float(n_left) / float(n_total);
|
||
|
|
normalize_right = float(n_right) / float(n_total);
|
||
|
|
}
|
||
|
|
|
||
|
|
float purity = purity_left * normalize_left + purity_right * normalize_right;
|
||
|
|
|
||
|
|
return purity;
|
||
|
|
}
|
||
|
|
|
||
|
|
protected:
|
||
|
|
virtual float Purity(const std::vector<TrainDatum>& targets, int depth) const = 0;
|
||
|
|
|
||
|
|
protected:
|
||
|
|
bool normalize_;
|
||
|
|
};
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
class ClassificationIGSplitEvaluator : public SplitEvaluator {
|
||
|
|
public:
|
||
|
|
ClassificationIGSplitEvaluator(bool normalize, int n_classes)
|
||
|
|
: SplitEvaluator(normalize), n_classes_(n_classes) {}
|
||
|
|
virtual ~ClassificationIGSplitEvaluator() {}
|
||
|
|
|
||
|
|
protected:
|
||
|
|
virtual float Purity(const std::vector<TrainDatum>& targets, int depth) const {
|
||
|
|
if(targets.size() == 0) return 0;
|
||
|
|
|
||
|
|
std::vector<int> ps;
|
||
|
|
ps.resize(n_classes_, 0);
|
||
|
|
for(auto target : targets) {
|
||
|
|
auto ctarget = std::static_pointer_cast<ClassificationTarget>(target.optimize_target);
|
||
|
|
ps[ctarget->cl()] += 1;
|
||
|
|
}
|
||
|
|
|
||
|
|
float h = 0;
|
||
|
|
for(int cl = 0; cl < n_classes_; ++cl) {
|
||
|
|
float fi = float(ps[cl]) / float(targets.size());
|
||
|
|
if(fi > 0) {
|
||
|
|
h = h - fi * std::log(fi);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
return h;
|
||
|
|
}
|
||
|
|
|
||
|
|
private:
|
||
|
|
int n_classes_;
|
||
|
|
};
|
||
|
|
|