1.在尾部添加一项

This has no effect if the element is already present

>>> a = set([1,2,3,4,5])

>>> a

set([1, 2, 3, 4, 5, 'shaw'])

2．清空集合中所有元素

clear(...)

Remove all elements from this set

>>>a = set([1, 2, 3, 4, 5, 'shaw'])

>>>a.clear()

>>>a

set([])

3.返回一个新集合，但是新集合中的元素，a中有，b中没有

difference(...)

>>> a = set([1, 2, 3, 4, 5,'shaw'])

>>> b = set([2,3,5,'sam'])

>>> a.difference(b)

set([1, 4, 'shaw'])

4.set a中删除，集合a和集合b同时拥有的元素

difference_update(...)

>>> a = set([1, 2, 3, 4, 5,'shaw'])

>>> b = set([2,3,5,'sam'])

>>> a.difference_update(b)

>>> a

set([1, 4, 'shaw'])

>>> b

set([2, 3, 5, 'sam'])

5.删除set中指定元素（即使这个元素不存在与这个集合中，不会报错）

Remove an element from a set if it is amember.f the element is not a member, do nothing.

>>> a = set([1, 2, 3, 4, 5,'shaw'])

>>> a

set([1, 2, 3, 4, 5, 'shaw'])

>>> a

set([1, 2, 3, 4, 5, 'shaw'])

6.返回一个新集合，新集合元素由set aset b的交集组成

intersection(...)

Return the intersection of two or more setsas a new set.

>>> a = set([1, 2, 3, 4, 5,'shaw'])

>>> b = set([2,3,5,'sam'])

>>> a.intersection(b) 等同于  a & b

set([2, 3, 5])

7.set a中删除，ab交集之外的元素

intersection_update(...)

>>> a = set([1, 2, 3, 4, 5,'shaw'])

>>> b = set([2,3,5,'sam'])

>>> a.intersection_update(b)

>>> a

set([2, 3, 5])

8.判断两个集合是否有交集，如果有，则返回True,否则返回False

isdisjoint(...)

>>> a = set([1, 2, 3, 4, 5,'shaw'])

>>> b = set([2,3,5,'sam'])

>>> a.isdisjoint(b)

False

>>> c = set([9,'alices'])

>>> a.isdisjoint(c)

True

9．测试一个集合中的元素是否都在另一个元素中（即测试集合b是否是集合a的子集）

issubset(...)

Report whether another set contains this set

注：

issuperset(...)

Report whether this set contains another set

>>> a = set([1, 2, 3, 4, 5,'shaw'])

>>> b = set([2,3,5,'sam'])

>>> c = set([5,'shaw'])

>>> b.issubset(a)

False

>>> c.issubset(a)  等同于 c <= a

True

10.删除一个元素（默认删除第一项），如果要删除的元素不存在，则报keyerror

pop(...)

>>>a = set([1, 2, 3, 4, 5, 'shaw'])

>>>a.pop()

1

>>>a

set([2,3, 4, 5, 'shaw'])

11. 删除指定元素，如果要删除的元素不存在，则报keyerror

remove(...)

>>> a = set([1, 2, 3, 4, 5,'shaw'])

>>> a.remove(1)

>>> a

set([2, 3, 4, 5, 'shaw'])

>>> a.remove('shaw')

>>> a

set([2, 3, 4, 5])

12.对称差集（此元素在a中有且b中没有，和b中有且a中没有的元素）

symmetric_difference(...)

>>> a = set('abcdef')

>>> b = set('abcklyt')

>>> a.symmetric_difference(b)

set(['e', 't', 'f', 'y', 'k', 'l', 'd'])

>>> a ^ b

set(['e', 't', 'f', 'y', 'k', 'l', 'd'])

13.取并集（返回一个新的 set 包含 s t 中的每一个元素）

union(...)

>>> a = set('acdf')

>>> a.union(b)

set(['a', 'c', 'd', 'f', 'h', 'k'])

>>> a | b

set(['a', 'c', 'd', 'f', 'h', 'k'])

14.向集合a中添加元素（添加另一个集合时，会去除重复的元素）

update(...)

>>> a = set('acdf')

>>> a.update(b)

>>> a

set(['a', 'c', 'd', 'f', 'h', 'k'])

>>> a = set('acdf')

>>> a |= b

>>> a

set(['a', 'c', 'd', 'f', 'h', 'k'])

>>> a= set('shaw')

>>> a.update('bnga')

>>> a

set(['a', 'b', 'g', 'h', 'n', 's', 'w'])