Python中的条件计数

Question

如果我有以下情况：

team = [
    {'name': 'Ben', 'age': 31, 'country': 'France', 'hobbies': ['coding', 'biking']},
    {'name': 'Quinn', 'age': 26, 'country': 'Ireland', 'hobbies': ['skiing']},
    {'name': 'Sasha', 'age': 24, 'country': 'Lebanon', 'hobbies': ['sports']},
    {'name': 'Alex', 'age': 28, 'country': 'Austria', 'hobbies': []}
]

对于一个人来说，我怎样才能算出“业余爱好”中的项目，比如说本。我尝试了let()、sum()和一些If语句，但都没有效果。也许我只是在语法上弄错了，或者错过了一步。能帮我找到正确的方向吗？

我怎样才能打印列出的兴趣爱好的数量，例如，本2，萨沙1等等。

Answer 1

使用len，如下所示：

team = [
    {'name': 'Ben', 'age': 31, 'country': 'France', 'hobbies': ['coding', 'biking']},
    {'name': 'Quinn', 'age': 26, 'country': 'Ireland', 'hobbies': ['skiing']},
    {'name': 'Sasha', 'age': 24, 'country': 'Lebanon', 'hobbies': ['sports']},
    {'name': 'Alex', 'age': 28, 'country': 'Austria', 'hobbies': []}
]


for player in team:
    print('%s has %d hobbies' % (player['name'], len(player['hobbies'])))

输出：

Ben has 2 hobbies
Quinn has 1 hobbies
Sasha has 1 hobbies
Alex has 0 hobbies

Answer 2

嗯，你可以试试这样的东西：

counts = {person["name"]:len(person.get("hobbies",[])) for person in team}

Answer 3

或者您可以使用.__len__()作为解决方案：

team = [
    {'name': 'Ben', 'age': 31, 'country': 'France', 'hobbies': ['coding', 'biking']},
    {'name': 'Quinn', 'age': 26, 'country': 'Ireland', 'hobbies': ['skiing']},
    {'name': 'Sasha', 'age': 24, 'country': 'Lebanon', 'hobbies': ['sports']},
    {'name': 'Alex', 'age': 28, 'country': 'Austria', 'hobbies': []}
]

for person in team:
    if person["hobbies"].__len__() > 1:
        print(person["name"],"has",str(person["hobbies"].__len__()),"hobbies")
    else:
        print(person["name"],"has",str(person["hobbies"].__len__()),"hobby")

产出：

Ben has 2 hobbies
Quinn has 1 hobby
Sasha has 1 hobby
Alex has 0 hobby