内置数据结构

 # 创建空列表
 empty_list = []
 empty_list = list()
 # 创建带有初始元素的列表
 numbers = [1, 2, 3, 4, 5]
 fruits = ["apple", "banana", "cherry"]
 mixed = [1, "apple", True, 3.14]
 # 使用列表推导式创建列表
 squares = [x ** 2 for x in range(10)]
 print(squares) # 输出: [0, 1, 4, 9, 16, 25, 36, 49, 64, 81]
 # 使用range创建列表
 numbers = list(range(1, 10, 2))
 print(numbers) # 输出: [1, 3, 5, 7, 9]
 # 复制列表
 original = [1, 2, 3]
 copy1 = original.copy()
 copy2 = list(original)
 copy3 = original[:] # 切片复制

 fruits = ["apple", "banana", "cherry"]
 # 通过索引访问元素
 print(fruits[0]) # 输出: apple
 print(fruits[1]) # 输出: banana
 print(fruits[-1]) # 输出: cherry (负索引从末尾开始)
 # 切片操作
 print(fruits[1:3]) # 输出: ['banana', 'cherry'] (从索引1到2)
 print(fruits[:2]) # 输出: ['apple', 'banana'] (从开始到索引1)
 print(fruits[1:]) # 输出: ['banana', 'cherry'] (从索引1到结束)
 print(fruits[::-1]) # 输出: ['cherry', 'banana', 'apple'] (反转列表)
 # 检查元素是否存在
 print("apple" in fruits) # 输出:
 print("orange" in fruits) # 输出: False
 # 获取列表长度
 print(len(fruits)) # 输出: 3

 fruits = ["apple", "banana", "cherry"]
 # 修改元素
 fruits[1] = "grape"
 print(fruits) # 输出: ['apple', 'grape', 'cherry']
 # 添加元素
 fruits.append("orange") # 在末尾添加
 print(fruits) # 输出: ['apple', 'grape', 'cherry', 'orange']
 fruits.insert(1, "pear") # 在指定位置插入
 print(fruits) # 输出: ['apple', 'pear', 'grape', 'cherry', 'orange']
 # 扩展列表
 more_fruits = ["mango", "kiwi"]
 fruits.extend(more_fruits) # 添加另一个列表的所有元素
 print(fruits) # 输出: ['apple', 'pear', 'grape', 'cherry', 'orange', 'mango', 'kiwi']
 # 删除元素
 fruits.remove("cherry") # 移除指定值的元素
 print(fruits) # 输出: ['apple', 'pear', 'grape', 'orange', 'mango', 'kiwi']
 popped = fruits.pop() # 移除并返回最后一个元素
 print(popped) # 输出: kiwi
 print(fruits) # 输出: ['apple', 'pear', 'grape', 'orange', 'mango']
 popped = fruits.pop(1) # 移除并返回指定位置的元素
 print(popped) # 输出: pear
 print(fruits) # 输出: ['apple', 'grape', 'orange', 'mango']
 # 清空列表
 fruits.clear()
 print(fruits) # 输出: []

 numbers = [3, 1, 4, 1, 5, 9, 2, 6]
 # 排序
 numbers.sort()
 print(numbers) # 输出: [1, 1, 2, 3, 4, 5, 6, 9]
 # 反向排序
 numbers.sort(reverse=True)
 print(numbers) # 输出: [9, 6, 5, 4, 3, 2, 1, 1]
 # 指定排序规则：key 传一个函数，按其返回值排
 fruits_by_len = ["kiwi", "apple", "fig"]
 fruits_by_len.sort(key=len)
 print(fruits_by_len) # 输出: ['fig', 'kiwi', 'apple']
 # key 与 reverse 可以组合
 fruits_by_len.sort(key=len, reverse=True)
 print(fruits_by_len) # 输出: ['apple', 'kiwi', 'fig']
 # 反转列表
 numbers.reverse()
 print(numbers) # 输出: [1, 1, 2, 3, 4, 5, 6, 9]
 # 统计元素出现次数
 print(numbers.count(1)) # 输出: 2
 # 查找元素索引
 print(numbers.index(5)) # 输出: 5
 # 列表拼接
 list1 = [1, 2, 3]
 list2 = [4, 5, 6]
 combined = list1 + list2
 print(combined) # 输出: [1, 2, 3, 4, 5, 6]
 # 列表重复
 repeated = [1, 2] * 3
 print(repeated) # 输出: [1, 2, 1, 2, 1, 2]

 # 创建元组
 empty_tuple = ()
 empty_tuple = tuple()
 # 创建带有初始元素的元组
 numbers = (1, 2, 3, 4, 5)
 fruits = ("apple", "banana", "cherry")
 mixed = (1, "apple", True, 3.14)
 # 注意: 单个元素的元组需要加逗号
 single_element = (1,)
 print(type(single_element)) # 输出: <class 'tuple'>
 # 不带括号的元组
 implicit_tuple = 1, 2, 3
 print(type(implicit_tuple)) # 输出: <class 'tuple'>
 # 从其他序列创建元组
 list_to_tuple = tuple([1, 2, 3])
 print(list_to_tuple) # 输出: (1, 2, 3)
 string_to_tuple = tuple("hello")
 print(string_to_tuple) # 输出: ('h', 'e', 'l', 'l', 'o')

 fruits = ("apple", "banana", "cherry")
 # 通过索引访问元素
 print(fruits[0]) # 输出: apple
 print(fruits[1]) # 输出: banana
 print(fruits[-1]) # 输出: cherry
 # 切片操作
 print(fruits[1:3]) # 输出: ('banana', 'cherry')
 print(fruits[:2]) # 输出: ('apple', 'banana')
 print(fruits[1:]) # 输出: ('banana', 'cherry')
 print(fruits[::-1]) # 输出: ('cherry', 'banana', 'apple')
 # 检查元素是否存在
 print("apple" in fruits) # 输出:
 # 获取元组长度
 print(len(fruits)) # 输出: 3
 # 元组的不可变性
 # fruits[1] = "grape" # 错误: 'tuple' object does not support item assignment

 # 基本解包
 coordinates = (10, 20, 30)
 x, y, z = coordinates
 print(x, y, z) # 输出: 10 20 30
 # 部分解包
 numbers = (1, 2, 3, 4, 5)
 first, *middle, last = numbers
 print(first) # 输出: 1
 print(middle) # 输出: [2, 3, 4]
 print(last) # 输出: 5
 # 交换变量
 a, b = 1, 2
 a, b = b, a
 print(a, b) # 输出: 2 1
 # 函数返回多个值
 def get_user():
  return "Alice", 30, "New York"
 name, age, city = get_user()
 print(name, age, city) # 输出: Alice 30 New York

 numbers = (3, 1, 4, 1, 5, 9)
 # 统计元素出现次数
 print(numbers.count(1)) # 输出: 2
 # 查找元素索引
 print(numbers.index(5)) # 输出: 4
 # 元组拼接
 tuple1 = (1, 2, 3)
 tuple2 = (4, 5, 6)
 combined = tuple1 + tuple2
 print(combined) # 输出: (1, 2, 3, 4, 5, 6)
 # 元组重复
 repeated = (1, 2) * 3
 print(repeated) # 输出: (1, 2, 1, 2, 1, 2)

 # 创建空字典
 empty_dict = {}
 empty_dict = dict()
 # 创建带有初始键值对的字典
 person = {"name": "Alice", "age": 30, "city": "New York"}
 # 使用dict()构造函数
 person = dict(name="Alice", age=30, city="New York")
 # 从键值对列表创建
 items = [("name", "Alice"), ("age", 30), ("city", "New York")]
 person = dict(items)
 # 从两个列表创建（键和值）
 keys = ["name", "age", "city"]
 values = ["Alice", 30, "New York"]
 person = dict(zip(keys, values))
 # 字典推导式
 squares = {x: x**2 for x in range(5)}
 print(squares) # 输出: {0: 0, 1: 1, 2: 4, 3: 9, 4: 16}
 # 带条件的字典推导式：只保留满足条件的键值对
 even_squares = {x: x**2 for x in range(10) if x % 2 == 0}
 print(even_squares) # 输出: {0: 0, 2: 4, 4: 16, 6: 36, 8: 64}

 person = {"name": "Alice", "age": 30, "city": "New York"}
 # 通过键访问值
 print(person["name"]) # 输出: Alice
 print(person["age"]) # 输出: 30
 # 使用get()方法访问（更安全）
 print(person.get("name")) # 输出: Alice
 print(person.get("country", "Unknown")) # 输出: Unknown（键不存在时返回默认值）
 # 检查键是否存在
 print("name" in person) # 输出:
 print("country" in person) # 输出: False
 # 获取所有键
 print(person.keys()) # 输出: dict_keys(['name', 'age', 'city'])
 # 获取所有值
 print(person.values()) # 输出: dict_values(['Alice', 30, 'New York'])
 # 获取所有键值对
 print(person.items()) # 输出: dict_items([('name', 'Alice'), ('age', 30), ('city', 'New York')])

 person = {"name": "Alice", "age": 30, "city": "New York"}
 # 添加或修改键值对
 person["country"] = "USA" # 添加新键值对
 print(person) # 输出: {'name': 'Alice', 'age': 30, 'city': 'New York', 'country': 'USA'}
 person["age"] = 31 # 修改现有值
 print(person) # 输出: {'name': 'Alice', 'age': 31, 'city': 'New York', 'country': 'USA'}
 # 使用update()方法更新
 person.update({"city": "Boston", "job": "Engineer"})
 print(person) # 输出: {'name': 'Alice', 'age': 31, 'city': 'Boston', 'country': 'USA', 'job': 'Engineer'}
 # 删除键值对
 removed_value = person.pop("country") # 移除并返回值
 print(removed_value) # 输出: USA
 print(person) # 输出: {'name': 'Alice', 'age': 31, 'city': 'Boston', 'job': 'Engineer'}
 # del 语句删除：不返回值，键不存在时抛 KeyError
 del person["city"]
 # setdefault：键不存在时写入默认值并返回它；已存在则原样返回现有值（不覆盖）
 person.setdefault("country", "USA")
 person.setdefault("country", "Canada")
 print(person["country"]) # 输出: USA —— 第一次 setdefault 已生效，第二次不覆盖
 # 删除最后一个键值对（Python 3.7+）
 last_item = person.popitem()
 print(last_item) # 输出: ('job', 'Engineer')
 print(person) # 输出: {'name': 'Alice', 'age': 31, 'city': 'Boston'}
 # 清空字典
 person.clear()
 print(person) # 输出: {}

 person = {"name": "Alice", "age": 30, "city": "New York"}
 # 遍历键
 for key in person:
  print(key)
 # 遍历键（显式）
 for key in person.keys():
  print(key)
 # 遍历值
 for value in person.values():
  print(value)
 # 遍历键值对
 for key, value in person.items():
  print(f"{key}: {value}")

 # 创建空集合
 empty_set = set() # 注意: {} 创建的是空字典
 # 创建带有初始元素的集合
 numbers = {1, 2, 3, 4, 5}
 fruits = {"apple", "banana", "cherry"}
 # 从其他序列创建集合
 list_to_set = set([1, 2, 3, 3, 4, 5])
 print(list_to_set) # 输出: {1, 2, 3, 4, 5}（自动去重）
 string_to_set = set("hello")
 print(string_to_set) # 输出: {'h', 'e', 'l', 'o'}（自动去重）
 # 集合推导式
 squares = {x**2 for x in range(5)}
 print(squares) # 输出: {0, 1, 4, 9, 16}
 # 带条件的集合推导式
 even_squares = {x**2 for x in range(10) if x % 2 == 0}
 print(even_squares) # 输出: {0, 4, 16, 36, 64}

 fruits = {"apple", "banana", "cherry"}
 # 添加元素
 fruits.add("orange")
 print(fruits) # 输出: {'apple', 'banana', 'cherry', 'orange'}
 # 添加多个元素
 fruits.update(["mango", "kiwi"])
 print(fruits) # 输出: {'apple', 'banana', 'cherry', 'orange', 'mango', 'kiwi'}
 # 删除元素
 fruits.remove("cherry") # 如果元素不存在会抛出错误
 print(fruits) # 输出: {'apple', 'banana', 'orange', 'mango', 'kiwi'}
 fruits.discard("grape") # 如果元素不存在不会抛出错误
 print(fruits) # 输出: {'apple', 'banana', 'orange', 'mango', 'kiwi'}
 # 移除并返回任意元素
 popped = fruits.pop()
 print(popped) # 输出: 任意元素，如 'apple'
 print(fruits) # 输出: 剩余元素
 # 清空集合
 fruits.clear()
 print(fruits) # 输出: set()

 set1 = {1, 2, 3, 4, 5}
 set2 = {4, 5, 6, 7, 8}
 # 并集
 union = set1 | set2
 print(union) # 输出: {1, 2, 3, 4, 5, 6, 7, 8}
 print(set1.union(set2)) # 同上
 # 交集
 intersection = set1 & set2
 print(intersection) # 输出: {4, 5}
 print(set1.intersection(set2)) # 同上
 # 差集
 difference = set1 - set2
 print(difference) # 输出: {1, 2, 3}
 print(set1.difference(set2)) # 同上
 # 对称差集（并集减去交集）
 symmetric_difference = set1 ^ set2
 print(symmetric_difference) # 输出: {1, 2, 3, 6, 7, 8}
 print(set1.symmetric_difference(set2)) # 同上
 # 子集检查
 set3 = {1, 2, 3}
 print(set3.issubset(set1)) # 输出:
 # 超集检查
 print(set1.issuperset(set3)) # 输出:
 # 不相交检查
 set4 = {6, 7, 8}
 print(set1.isdisjoint(set4)) # 输出:

frozen = frozenset([1, 2, 3])
# frozen.add(4)  # 报错: AttributeError: 'frozenset' object has no attribute 'add'

# 典型用途：把"一组权限"当作字典的键做映射
permissions = {
    frozenset(["read", "write"]): "editor",
    frozenset(["read"]): "viewer",
}
print(permissions[frozenset(["read", "write"])]) # 输出: editor

# 嵌套字典列表：一组用户记录（典型 JSON 数组）
users = [
    {"name": "Alice", "age": 30},
    {"name": "Bob", "age": 25},
]
print(users[0]["name"]) # 输出: Alice（先取第 0 个字典，再取它的 name 键）

# 嵌套字典字典：按行组织的矩阵
matrix = {
    "row1": {"col1": 1, "col2": 2},
    "row2": {"col1": 3, "col2": 4},
}
print(matrix["row2"]["col1"]) # 输出: 3