Set

>>> a = {1, 2, 4, 5, 5}
>>> a
{1, 2, 4, 5}
>>> a.add(7)
>>> a
{1, 2, 4, 5, 7}
>>> a.discard(4)
>>> a
{1, 2, 5, 7}
>>> b = {1, 2, 3}
>>> a | b       #并集
{1, 2, 3, 5, 7}
>>> a.union(b)     
{1, 2, 3, 5, 7}
>>> a & b       #交集
{1, 2}
>>> a.intersection(b)
{1, 2}
>>> a - b       #差集
{5, 7}
>>> a.difference(b)
{5, 7}
>>> a ^ b     #对称差集，返回两个集合中不重复的元素
{3, 5, 7}
>>> a.symmetric_difference(b)
{3, 5, 7}
>>> a
{1, 2, 5, 7}
>>> b
{1, 2, 3}
>>> b.update([2, 5, 6])   #有点像extend
>>> b
{1, 2, 3, 5, 6}
>>> b.update((2, 5, 6))   #省掉一个括号会出错
>>> b
{1, 2, 3, 5, 6}
>>> b.pop()      #随意去一个
1
>>> b
{2, 3, 5, 6}

>>> c = {1, 2}
>>> d = {3, 4}
>>> c.isdisjoint(d)   #判断是否无交集
True
>>> e = {2, 5}
>>> c.isdisjoint(e)
False
>>> f = {2, 5, 8}
>>> e.issubset(f)     #判断子集
True
>>> f.issubset(e)
False
>>> e.issuperset(f)    #判断父集
False
>>> f.issuperset(e)
True
>>> f.difference_update(e)  #取差集然后更新f
>>> e
{2, 5}
>>> f
{8}