苦练Python第25天：玩转字典

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欢迎来到《100天Python》第25天！今天我们将彻底征服 Python 最灵活的数据结构------字典（dictionary）。无论是 JSON 还是 API 响应，字典无处不在。掌握它，你的数据查询将快如闪电。🐍⚡

字典是无序、可变的键值对集合。

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person = {
    "name": "Alice",
    "age": 30,
    "city": "New York"
}

键唯一，值可为任意类型。

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empty = {}
user = dict(name="John", age=25)

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print(person["name"])           # Alice
print(person.get("age"))        # 30
print(person.get("email", "N/A"))  # N/A

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person["age"] = 31              # 修改
person["email"] = "a@b.com"     # 新增

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person.pop("age")     # 按键删除并返回值
del person["city"]    # 直接删除
person.clear()        # 清空

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for k, v in person.items():
    print(f"{k}: {v}")

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users = {
    "alice": {"age": 30, "city": "Paris"},
    "bob": {"age": 25, "city": "Berlin"}
}
print(users["alice"]["city"])  # Paris

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squares = {x: x*x for x in range(5)}
# {0: 0, 1: 1, 2: 4, 3: 9, 4: 16}

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text = "apple banana apple orange"
counts = {}
for w in text.split():
    counts[w] = counts.get(w, 0) + 1
print(counts)

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response = {
    "status": "success",
    "data": {"user": "Alice", "id": 123}
}
print(response["data"]["user"])  # Alice

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products = {101: "Shoes", 102: "Shirt", 103: "Bag"}
print(products[102])  # Shirt

最后感谢阅读！欢迎关注我，微信公众号 ：倔强青铜三。欢迎点赞、收藏、关注，一键三连！！！