分类
可变集合：
创建
字面量创建
{值}
值： 整形 字符串 元组
只能是固定类型，不可以是列表，可以是元组
>>> {1,2,3,}
{1, 2, 3}
>>> {1,"s"}
{1, 's'}
>>> {1,1.2,True}
{1, 1.2}
>>> {11,True}
{True, 11}
通过对象创建
set()
>>> set2 = set("hello")
>>> set
<class 'set'>
>>> set2
{'l', 'e', 'h', 'o'}
>>> set3 = set([1,2,3,4])
>>> set3
{1, 2, 3, 4}
frozenset()
>>> set3 = frozenset("hello")
>>> set3
frozenset({'l', 'e', 'h', 'o'})
推导式
>>> {x*x for x in range(5)}
{0, 1, 4, 9, 16}
不可变集合：
交集
>>> {1,False}
{False, 1}
>>> {1,1.0}
{1}
>>> {1,True}
{1}
集合的操作
遍历访问：
>>> set1 = {1,2,3,6,7,8,5,4}
>>> for i in set1:
print(i,end="")
12345678
成员判断
in
not in
>>> set1={1,2,3}
>>> set2 = {2,3,4,5,6}
并集
>>> set1| set2
{1, 2, 3, 4, 5, 6}
交集
>>> set1 & set2
{2, 3}
差集
>>> set1 - set2
{1}
对差
>>> set1 ^ set2
{1, 4, 5, 6}
>>> set1==set2
False
>>> set1>set2
False
>>> set1<set2
False
>>> len(set1)
3
集合的合并
>>> set1
{1, 2, 3}
>>> set2
{2, 3, 4, 5, 6}
>>> set1.update(set2)
>>> set1
{1, 2, 3, 4, 5, 6}
copy():
>>> set1
{1, 2, 3, 4, 5}
>>> set2 = set1.copy()
>>> set2
{1, 2, 3, 4, 5}
不支持索引
