计数器似乎添加不正确

Question

当我测试一个计数器时，我发现它似乎只显示最后一个通过它的项目。例如，如果某个东西是优秀的，那么它显示为“1”。但是，不管其他数据如何，其余的都是0。你知道吗

def mealrating(score, review):
    for x in range(0,len(score)):

        mp = 0
        mg = 0
        me = 0
        if score[x] >= 1 and score[x] <= 3:
            review.append("poor")
            mp = mp + 1

        if score[x] >= 4 and score[x] <= 6:
            review.append("good")
            mg = mg + 1

        if score[x] >= 7 and score[x] <= 10:
            review.append("excellent")
            me = me + 1

    print("The customer rated tonight's meal as:")
    print('Poor:' + str(mp))
    print('Good:' + str(mg))
    print('Excellent:' + str(me))
    print("\n")

Answer 1

在每次迭代中，您都要重置mp、mg和me。你知道吗

def mealrating(score, review):
    mp = 0
    mg = 0
    me = 0

    for x in range(0,len(score)):
        if score[x] >= 1 and score[x] <= 3:
            review.append("poor")
            mp = mp + 1

        if score[x] >= 4 and score[x] <= 6:
            review.append("good")
            mg = mg + 1

        if score[x] >= 7 and score[x] <= 10:
            review.append("excellent")
            me = me + 1

    print("The customer rated tonight's meal as:")
    print('Poor:' + str(mp))
    print('Good:' + str(mg))
    print('Excellent:' + str(me))
    print("\n")

Answer 2

必须在循环外初始化计数器：

mp = 0
mg = 0
me = 0
for x in range(0, len(score)):
    # same as before

否则每次迭代都会被重置！要使代码更具python风格，请考虑以下提示：

• 形式为x >= i and x <= j的条件可以更简洁地写成i <= x <= j
• 遍历列表的惯用方法是使用迭代器，而不显式使用索引
• 这些条件是互斥的，因此应该使用elif
• 使用+=递增变量

这就是我的意思：

mp = mg = me = 0
for s in score:
    if 1 <= s <= 3:
        review.append("poor")
        mp += 1
    elif 4 <= s <= 6:
        # and so on