集合

集合set，{}

可变的数据类型，里面储存的元素必须是不可变数据类型，无序，元素不能重复：去重，列表可转换成集合，自动去重

1、增加，add

set1 = {'seven','wenzi','娃哈哈'}
set1.add('旺仔')
print(set1)

2、迭代增加，update

set1 = {'seven','wenzi','娃哈哈'}
set1.update('旺仔牛奶')
print(set1)

3、删除，pop，随机删除，有返回值

set1 = {'seven','wenzi','娃哈哈'}
set1.update('旺仔牛奶')
set1.pop()
print(set1)

4、按元素删除，remove，没有该元素会报错

set1 = {'seven','wenzi','娃哈哈'}
set1.remove('娃哈哈')

5、清空集合，clear，空集合set()

set1 = {'seven','wenzi','娃哈哈'}
set1.clear()

6、删除集合del

set1 = {'seven','wenzi','娃哈哈'}
del set1

7、查询：for循环，无序

8、交集

set1 = {1,2,3,4,5}
set2 = {4,5,6,7,8}
print(set1 & set2)
print(set1.intersection(set2))

9、并集

set1 = {1,2,3,4,5}
set2 = {4,5,6,7,8}
print(set1 | set2)
print(set1.union(set2))

10、反交集

set1 = {1,2,3,4,5}
set2 = {4,5,6,7,8}
print(set1 ^ set2)
print(set1.symmetric_difference(set2) )

11、差集，独有的

set1 = {1,2,3,4,5}
set2 = {4,5,6,7,8}
print(set1 - set2)
print(set1.difference(set2))

12、子集与超集，返回布尔值

set1 = {1,2,3,4}
set2 = {1,2,3,4,5,6,7,8}
print(set1 < set2)  #子集
print(set1.issubset(set2))

set1 = {1,2,3,4}
set2 = {1,2,3,4,5,6,7,8}
print(set2 > set1)  #超集
print(set2.issuperset(set1))

 

13、冻结集合，frozenset，set集合就变成了不可变的数据类型，只能查询

set1 = {1,2,3}
set2 = frozenset(set1)