set()运算

1 计算两个list的关系时,可转化为set进行运算.

参考：https://www.runoob.com/python3/python3-set.html

a =[1,4,3,5,6,6,7,7,7]
b =[2,2,3,3,1,1,22]
a = set(a)
b = set(b)
# a与b的差集
print(a - b)
# a与b的交集
print(a & b)
print(a.intersection(b))
# a与b的并集
print(a | b)
print(a.union(b))
# 不同时包含于a和b的元素,类似于symmetric_difference_update函数
print(a ^ b)
# {4, 5, 6, 7}
# {1, 3}
# {1, 3}
# {1, 2, 3, 4, 5, 6, 7, 22}
# {1, 2, 3, 4, 5, 6, 7, 22}
# {2, 4, 5, 6, 7, 22}

对于list中是字符串的情况同样可以使用

a = ['a','b','c','d']
b = ['a','b','p','q']
print( set(a) & set(b))
# {'a', 'b'}