101 lines
2.6 KiB
Python
101 lines
2.6 KiB
Python
# 字典中的作业 字典方法案例总结
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# 1. 创建字典并访问元素
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students = {'Alice': 20, 'Bob': 22, 'Charlie': 23}
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key = 'Bob'
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if key in students:
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print(f"'{key}' 的年龄是 {students[key]}")
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else:
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print(f"'{key}' 不在字典中")
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# 2. 向字典添加新键值对
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students = {'Alice': 20, 'Bob': 22}
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students['Charlie'] = 23
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print(f"更新后的字典是 {students}")
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# 3. 删除字典中的键值对
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students = {'Alice': 20, 'Bob': 22, 'Charlie': 23}
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del_key = 'Bob'
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if del_key in students:
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del students[del_key]
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print(f"删除后的字典是 {students}")
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else:
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print(f"'{del_key}' 不在字典中")
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# 4. 查找字典中是否存在某个键
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students = {'Alice': 20, 'Bob': 22, 'Charlie': 23}
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key = 'Charlie'
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if key in students:
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print(f"'{key}' 存在于字典中")
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else:
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print(f"'{key}' 不存在于字典中")
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# 5. 获取字典的所有键和值
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students = {'Alice': 20, 'Bob': 22, 'Charlie': 23}
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keys = list(students.keys())
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values = list(students.values())
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print(f"字典中的所有键是 {keys}")
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print(f"字典中的所有值是 {values}")
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# 6. 获取字典中所有键值对（项）
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students = {'Alice': 20, 'Bob': 22, 'Charlie': 23}
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items = list(students.items())
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print(f"字典中的所有项是 {items}")
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# 7. 使用 get() 方法访问字典中的值
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students = {'Alice': 20, 'Bob': 22, 'Charlie': 23}
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key = 'David'
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value = students.get(key, None) # 默认值为 None
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if value is None:
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print(f"'{key}' 不存在于字典中，返回默认值 {value}")
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else:
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print(f"'{key}' 的值是 {value}")
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# 8. 字典中值的最大值和最小值
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students = {'Alice': 20, 'Bob': 22, 'Charlie': 23}
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max_value = max(students.values())
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min_value = min(students.values())
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print(f"字典中值的最大值是 {max_value}")
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print(f"字典中值的最小值是 {min_value}")
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# 9. 字典的键值对反转
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students = {'Alice': 20, 'Bob': 22, 'Charlie': 23}
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reversed_dict = {v: k for k, v in students.items()}
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print(f"反转后的字典是 {reversed_dict}")
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# 10. 合并两个字典
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dict1 = {'Alice': 20, 'Bob': 22}
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dict2 = {'Charlie': 23, 'David': 24}
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merged_dict = {**dict1, **dict2} # Python 3.5+ 支持
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print(f"合并后的字典是 {merged_dict}")
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# 11. 计算字典中所有值的总和
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students = {'Alice': 20, 'Bob': 22, 'Charlie': 23}
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total = sum(students.values())
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print(f"字典中所有值的总和是 {total}")
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# 12. 字典的条件筛选
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set1 = {1, 2, 3}
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set2 = {1, 2, 3, 4, 5}
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if set1.issubset(set2):
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print("第一个集合是第二个集合的子集")
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else:
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print("第一个集合不是第二个集合的子集")
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