@Override
public double scoreSplit(ClassificationCounter a, ClassificationCounter b) {
ClassificationCounter parent = ClassificationCounter.merge(a, b);
double parentGiniIndex = getGiniIndex(parent);
double aGiniIndex = getGiniIndex(a) * a.getTotal() / parent.getTotal();
double bGiniIndex = getGiniIndex(b) * b.getTotal() / parent.getTotal();
return parentGiniIndex - aGiniIndex - bGiniIndex;
}
