public static double FMeasure(Item[] instances, DecisionForest forest, AttributeVariable target_attribute, double B = 1)
{
double precision = Precision(instances, forest, target_attribute);
double recall = Recall(instances, forest, target_attribute);
return((B * B + 1) * precision * recall / (B * B * precision + recall));
}
public static double Recall(Item[] instances, DecisionForest forest, AttributeVariable target_attribute)
{
int tp = 0, fn = 0;
foreach (var item in instances)
{
int true_value = (int)item.FindAttributeValue(target_attribute);
int predict_value = (int)Math.Round(forest.Decide(item));
if (true_value == 1)
{
if (predict_value == 1)
{
++tp;
}
else
{
++fn;
}
}
}
return((double)tp / (double)(tp + fn));
}