def calculate_precision_recall_F_metrics(algorithm_number, real_number,
    correct_number):
    """
    Result: (precision, recall, F)
    """
    if algorithm_number == 0:
        precision = 0
    else:
        precision = float(correct_number) / algorithm_number
    if real_number == correct_number:
        recall = 1
    else:
        recall = float(correct_number) / real_number
    return precision, recall, 2 * float(correct_number) / (real_number +
        algorithm_number)
