Python-集合 字典-set dict

集合 set
　　1. 无序
　　2. 去重
　　3. 定义空集 set()

numbers = {1, 3, 4, 5, 6, 5, 4, 4, 7, 8}
print(numbers)
print(numbers)

集合操作
　　1. 求差集 　　 - 　　  .difference
　　2. 求交集 　　 &　　 .intersection
　　3. 求并集　　 |　　 　.union

student_python = {"xiaoWang", "xiaoMing", "lvChaBiao", "baiLianHua"}
student_golang = {"xiaoWang", "beimenchuixue", "ximenchuifeng"}

print("only study python student: ", student_python - student_golang)
print("study python and golang student: ", student_python & student_golang)
print("total students : ", student_python | student_golang)

字典 dict
　　1. 定义空字典 dict() {}
　　2. 无序
　　3. key去重, 有重复key取最后的key对应的value值
　　4. {key: value,...}
　　value任意类型: int float bool str list tuple set dict
　　key必须是不可变类型 int float bool str tuple

student_score = {
    "xiaoWang": 99,
    "xiaoLi": 77,
    "beimenchuixue": 99,
    "lvChaBiao": 90,
    "ximenchuifeng": 88
}

print(student_score.get("beimenchuixue", None))
print(student_score.pop("lvChaBiao"))
student_score.update({
    "xiaoWang": 66,
})
print(student_score)
print(student_score.items())
print(student_score.keys())
print(student_score.values())

访问
　　1. 通过key访问value [key]
　　2. 安全访问方式 .get()

判断一个元素是否在集合中和字典的key是否在字典中 in

student_score = {
    "xiaoWang": 99,
    "xiaoLi": 77,
    "beimenchuixue": 99,
    "lvChaBiao": 90,
    "ximenchuifeng": 88
}

print("xiaoWang" in student_score)
print(99 in student_score)