更新分类器测试

def test_classifier(classifier, data, verbose=False): #1
    true_positives = 0 #2
    true_negatives = 0
    false_positives = 0
    false_negatives = 0
    for mileage, price, is_bmw in data:
        predicted = classifier(mileage,price)
        if predicted and is_bmw: #3
            true_positives += 1
        elif predicted:
            false_positives += 1
        elif is_bmw:
            false_negatives += 1
        else:
            true_negatives += 1
            
    if verbose:        
        print("true positives %f" % true_positives) #4
        print("true negatives %f" % true_negatives)
        print("false positives %f" % false_positives)
        print("false negatives %f" % false_negatives)
            
    return (true_positives + true_negatives) / len(data) #5