集合类型内置方法

目录

• 1.作用
• 2.定义方式
• 3.内置方法
• 4.存一个值还是多个值
• 5.有序 or 无序
• 6.可变 or 不可变(重点)

1.作用

是存储一大堆元素的东西，容器数据类型。用于关系运算的集合体，由于集合内的元素无序且集合元素不可重复，因此集合可以去重，但是去重后的集合会打乱原来元素的顺序。

2.定义方式

以{}用逗号隔开不可变数据类型

空大括号是字典，不是集合，定义空集合必须得用set()

s = {1,2,1,'a','a','c'}
print(s)

3.内置方法

## 优先掌握
# 1.长度len
pythoners = {'jason','nick','tank','sean'}
print(len(pythoners))

# 2.成员运算in和not in
print('nick' in pythoners)

pythoners = {'jason','nick','tank','sean'}
linuxers = {'nick','egon','kevin'}
# 3.并集|
print(pythoners | linuxers)
print(pythoners.union(linuxers))

# 4.交集&
print(pythoners & linuxers)
print(pythoners.intersection(linuxers))

# 5.差集
print(pythoners - linuxers)
print(pythoners.difference(linuxers))

# 6.对称差集^
print(pythoners ^ linuxers)
print(pythoners.symmetric_difference(linuxers))

# 7.==
print(pythoners == linuxers)

# 8.父集：>,>=
print(pythoners > linuxers)
print(pythoners >= linuxers)

# 9.子集：<,<=
print(pythoners < linuxers)
print(pythoners <= linuxers)

## 了解
pythoners = {'jason','nick','tank','sean'}
linuxers = {'nick','egon','kevin'}

# 随机删除
pythoners.pop()
print(pythoners)

pythoners.update(linuxers)
print(pythoners)

# 清空
pythoners.clear()
print(pythoners)

# 复制
print(pythoners.copy())

# 移除
pythoners.remove('nickk')  # 没有报错
print(pythoners)

pythoners.discard('nickk')  # 没有不报错
print(pythoners)

pythoners = {'jason','nick','tank','sean'}
pythoners2 = {'jason','nick','tank','sean','nick2'}
# 子集
print(pythoners.issubset(pythoners2))   
# 父集
print(pythoners.issuperset(pythoners2))  

pythoners = {'jason','nick','tank','sean'}
linuxers = {'nick','egon','kevin'}
pythoners.difference_update(linuxers)
print(pythoners)

pythoners.symmetric_difference_update(linuxers)
print(pythoners)

# isdisjoint() 集合没有共同的部分返回True,否则返回False
pythoners = {'jason','nick','tank','sean'}
linuxers = {'nick','egon','kevin'}
res = pythoners.isdisjoint(linuxers)
print(res)

4.存一个值还是多个值

多个值

5.有序 or 无序

无序

6.可变 or 不可变(重点)

可变

s = {1,2}
print(id(s))
s.add(3)
print(id(s))