Python 将一个目录列表映射成一个目录列表

我甚至不知道该怎么称呼它，所以很难找到它。比如我有,

people = [
    {"age": 22, "first": "John", "last": "Smith"},
    {"age": 22, "first": "Jane", "last": "Doe"},
    {"age": 41, "first": "Brian", "last": "Johnson"},
]

我想要像这样的东西

people_by_age = {
    22: [
        {"first": "John", "last": "Smith"},
        {"first": "Jane", "last": "Doe"},

    ],
    41: [
        {"first": "Brian", "last": "Johnson"}
    ]
}

---

在Python 2中，最干净的方法是什么？

只需循环并添加到新字典中：

people_by_age = {}
for person in people:
    age = person.pop('age')
    people_by_age.setdefault(age, []).append(person)

返回给定键的现有值，或者如果缺少该键，则使用第二个参数首先设置该键

演示：

使用方法和步骤

代码：

from collections import defaultdict

people = [
    {"age": 22, "first": "John", "last": "Smith"},
    {"age": 22, "first": "Jane", "last": "Doe"},
    {"age": 41, "first": "Brian", "last": "Johnson"},
]

d = defaultdict(int)

people_dic = defaultdict(list)
for element in people:
    age = element.pop('age')
    people_dic[age].append(element)

print(people_dic)

defaultdict(<type 'list'>, {41: [{'last': 'Johnson', 'first': 'Brian'}], 22: [{'last': 'Smith', 'first': 'John'}, {'last': 'Doe', 'first': 'Jane'}]})

输出：

from collections import defaultdict

people = [
    {"age": 22, "first": "John", "last": "Smith"},
    {"age": 22, "first": "Jane", "last": "Doe"},
    {"age": 41, "first": "Brian", "last": "Johnson"},
]

d = defaultdict(int)

people_dic = defaultdict(list)
for element in people:
    age = element.pop('age')
    people_dic[age].append(element)

print(people_dic)

defaultdict(<type 'list'>, {41: [{'last': 'Johnson', 'first': 'Brian'}], 22: [{'last': 'Smith', 'first': 'John'}, {'last': 'Doe', 'first': 'Jane'}]})

defaultdict（，{41:[{'last'：'Johnson'，'first'：'Brian'}]，22:[{'last'：'Smith'，'first'：'John'}，{'last'：'Doe'，'first'：'Jane'}）

谢谢！这完全回答了我的问题。