set 集合操作

#!/usr/bin/env python
# -*- coding:utf-8 -*-
# Author:woshinidaye
'''
集合两个功能：
1、去重。把一个列表变成一个集合，就自动去重了；
2、关系测试。测试两个列表的交集、并集、补集等关系；
'''

a = [1,2,2,3,4,5]
b = '1234567890'
e = 'hello'
print(a,'\n',set(a),'\n',b,'\n',set(b),'\n',e,'\n',set(e))            #自动吧重复了2去掉了
#集合业务无序的，因此也没有index
print('parting_1'.rjust(30,'>').ljust(60,'<'))

list_1 = [1,2,34,56,7,7,8,89]
list_1 = set(list_1)
list_2 = [4,4,5,6,7,1,2]
list_2 = set(list_2)
list_3 = set([1,2,7])
print(list_1,list_2)
#求交集，同时存在list_1 和 list_2
print(list_1.intersection(list_2))  #Return the intersection of two sets as a new set
print('>>>>>',list_1 & list_2)
#并集,list_1 list_2的并集，
print(list_1.union(list_2))     #Return the union of sets as a new set
print('>>>>>',list_1 | list_2)
#差集,只存在于list_1，不存在与list_2
print(list_1.difference(list_2))    #Return the difference of two or more sets as a new set.
print('>>>>>',list_1 - list_3)
#要么存在于list_1,要么存在于list_2，反正不能同时存在于两个list
print(list_1.symmetric_difference(list_2))  #Return the symmetric difference of two sets as a new set
print('>>>>>',list_1 ^ list_2)
#判断是不是子集，是不是父级
print(list_1.issubset(list_2),list_3.issubset(list_1),list_1.issuperset(list_3))
#判断有没有交集,如果没得交集，就返回True,否则为False
print(list_1.isdisjoint(list_2))    #Return True if two sets have a null intersection
#集合的用法还有，add、clear、copy、discard、pop、remove
'''
pop:Remove and return an arbitrary set element.Raises KeyError if the set is empty.
remove:Remove an element from a set; it must be a member. If the element is not a member, raise a KeyError.
discard:Remove an element from a set if it is a member.If the element is not a member, do nothing.
'''
print('ending'.rjust(30,'>').ljust(60,'<'))