python set

可变集合set   集合对象是一组无序排列的可哈希的值，集合成员可以做字典的键
s = set('12313 2')
print(s)

s1 = [1,2,3,1]

print(list(set(s1)))

报错
li = [[1,2],1,2]
set(li)
不可变集合 frozenset()
li = [1,'a','b']
s = set(li)
dic = {s:'123'}

集合取值/判断
遍历取值
li = [1,'ab','b']
s = set(li)
s.add('www')
print(s)
s.update([12,2])
print(s)
s.remove(1)
print(s)
s.pop()
print(s)
s.clear()
print(s)
清空 为空大空号都没了和删除不一样

in
li = [1,'a','b']
s = set(li)
print(2 in li)
not in

集合等价不等价

s = set('alex') == set('alexexex')

包含
print(set('alex') < set('alexw'))

a = set([1, 2, 3, 4, 5])
b = set([4, 5, 6, 7, 8])

交集
s = a.intersection(b)
s = a&b
print(s)

并集  |
s1 = a.union(b)
s1 = a | b
print(s1)

差集  a里面有b里面没有 -
s2 = a.difference(b)
s2 = a - b
print(s2)

对称差集
s3 = a.symmetric_difference(b)
s3 = a ^ b
print(s3)

父级  超集  >
print(a.issuperset(b))

子集 <
print(a.issubset(b))


短路
a = set([1, 2, 3, 4, 5, 9])
b = set([4, 5, 6, 7, 8])

print(a and b)

print(a or b)