# 字典示例

# 创建字典
student = {
    "name": "张三",
    "age": 15,
    "grade": "八年级",
    "subjects": ["数学", "语文", "英语"],
    "scores": {
        "数学": 95,
        "语文": 88,
        "英语": 92
    }
}

print("学生信息:")
print(student)

# 访问字典值
print("\n=== 访问字典 ===")
print("学生姓名:", student["name"])
print("学生年龄:", student.get("age"))
print("使用get带默认值:", student.get("address", "未提供"))

# 修改字典
print("\n=== 修改字典 ===")
student["age"] = 16  # 修改值
student["school"] = "第一中学"  # 添加新键值对
student.setdefault("class", "八(3)班")  # 如果键不存在则设置默认值
print("修改后的学生信息:", student)

# 删除元素
print("\n=== 删除元素 ===")
removed_grade = student.pop("grade")  # 删除并返回
print(f"删除的年级: {removed_grade}")

removed_item = student.popitem()  # 删除最后一个键值对
print(f"删除的最后一个项: {removed_item}")
print("删除后字典:", student)

# 遍历字典
print("\n=== 遍历字典 ===")
print("遍历键:")
for key in student:
    print(f"  {key}: {student[key]}")

print("\n遍历值:")
for value in student.values():
    print(f"  {value}")

print("\n遍历键值对:")
for key, value in student.items():
    print(f"  {key}: {value}")

# 字典嵌套
print("\n=== 字典嵌套 ===")
classroom = {
    "teacher": "王老师",
    "students": [
        {"name": "小明", "score": 95, "hobbies": ["篮球", "编程"]},
        {"name": "小红", "score": 88, "hobbies": ["绘画", "音乐"]},
        {"name": "小刚", "score": 92, "hobbies": ["足球", "阅读"]}
    ],
    "subject": "Python编程",
    "schedule": {
        "周一": "14:00-15:30",
        "周三": "14:00-15:30",
        "周五": "10:00-11:30"
    }
}

print("班级信息:")
print(f"老师: {classroom['teacher']}")
print(f"科目: {classroom['subject']}")

print("\n学生成绩:")
for student in classroom["students"]:
    print(f"  {student['name']}: {student['score']}分")

print("\n课程安排:")
for day, time in classroom["schedule"].items():
    print(f"  {day}: {time}")

# 字典推导式
print("\n=== 字典推导式 ===")
numbers = [1, 2, 3, 4, 5]
squares_dict = {x: x**2 for x in numbers}
print("数字平方字典:", squares_dict)

words = ["apple", "banana", "cherry", "date"]
length_dict = {word: len(word) for word in words}
print("单词长度字典:", length_dict)

# 过滤字典
scores = {"数学": 95, "语文": 88, "英语": 92, "物理": 78, "化学": 85}
good_scores = {subject: score for subject, score in scores.items() if score >= 85}
print("良好成绩科目:", good_scores)

# 字典合并
print("\n=== 字典合并 ===")
dict1 = {"a": 1, "b": 2}
dict2 = {"b": 3, "c": 4}  # 注意键"b"重复

# 方法1: update()
dict3 = dict1.copy()
dict3.update(dict2)
print("update()合并:", dict3)

# 方法2: **操作符 (Python 3.5+)
dict4 = {**dict1, **dict2}
print("**操作符合并:", dict4)

# 方法3: | 操作符 (Python 3.9+)
# dict5 = dict1 | dict2
# print("| 操作符合并:", dict5)

# 字典常用方法
print("\n=== 字典常用方法 ===")
inventory = {"苹果": 10, "香蕉": 5, "橙子": 8, "葡萄": 15}
print("库存字典:", inventory)

print("\n所有键:", list(inventory.keys()))
print("所有值:", list(inventory.values()))
print("所有键值对:", list(inventory.items()))

print("\n苹果数量:", inventory.get("苹果", 0))
print("梨子数量:", inventory.get("梨子", 0))

inventory_copy = inventory.copy()
print("字典副本:", inventory_copy)

print("\n清空字典...")
inventory.clear()
print("清空后:", inventory)