【5.4】set和frozenset 

 1 #!/user/bin/env python
 2 # -*- coding:utf-8 -*-
 3 # set集合 frozenset不可变集合， 无序、不重复
 4 # set()函数接收一个可迭代对象
 5 # s = set('abcdefa')
 6 s = {'a', 'b'}
 7 s.add('c')
 8 print(s)
 9 
10 # frozenset不可变集合,可以作为dict的key
11 fs = frozenset('abcd')
12 print(fs)
13 
14 # 向set添加数据
15 another_set = set('def')
16 s.update(another_set)
17 print(s)
18 
19 # difference,返回一个新的set s - another_set
20 re_set = s.difference(another_set)
21 print(re_set)
22 re_set = s - another_set
23 print(re_set)
24 # 交集
25 re_set = s & another_set
26 print(re_set)
27 # 并集
28 re_set = s | another_set
29 print(re_set)
30 
31 # 实现__contains__魔法函数
32 if 'a' in s:
33     print('i am in set')
34 
35 # issubset判断是不是子集
36 a = {'a', 'b'}
37 b = {'a'}
38 re = b.issubset(a)
39 print(re)
{'b', 'a', 'c'}
frozenset({'b', 'a', 'd', 'c'})
{'c', 'a', 'f', 'b', 'e', 'd'}
{'c', 'a', 'b'}
{'c', 'a', 'b'}
{'e', 'd', 'f'}
{'b', 'f', 'c', 'a', 'e', 'd'}
i am in set
True

　　

posted @ 2019-07-26 15:44  _simpleSmile  阅读(183)  评论(0)    收藏  举报