Python之set集合的相关介绍

>>> l1=[1,2,3,4,5,6]

>>> s1=set(l1)

>>> print(s1)

{1, 2, 3, 4, 5, 6}

>>> s2={6,7,8,9,10}

>>> print(s2)

{8, 9, 10, 6, 7}

>>> s3={i for i in range(10)}

>>> print(s3)

{0, 1, 2, 3, 4, 5, 6, 7, 8, 9}

为集合增加一个元素，如果集合中本来已经存在这个元素对集合无影响

Add an element to a set.

This has no effect if the element is already present.

>>> s1={1,2,3,4,5,6,7}

>>> s1.add(8)

>>> print(s1)

{1, 2, 3, 4, 5, 6, 7, 8}

>>> s1.add(9)

>>> print(s1)

{1, 2, 3, 4, 5, 6, 7, 8, 9}

清空集合里所有的元素

Remove all elements from this set.

>>> s1={1,2,3,4,5,6,7}

>>> s2={5,6,7,8,9}

>>> s1.clear()

>>> print(s1)

set()

>>> s2.clear()

>>> print(s2)

set()

对集合进行浅拷贝(只复制元素，不复制内存地址)

Return a shallow copy of a set.

>>> s1={1,2,3,4,5,6,7}

>>> print(s1,id(s1))

{1, 2, 3, 4, 5, 6, 7} 140509859430472

>>> s2=s1.copy()

>>> print(s2,id(s2))

{1, 2, 3, 4, 5, 6, 7} 140509842716712

求两个或多个集合的差集，并返回一个新集合

Return the difference of two or more sets as a new set.

>>> s1={1,2,3,4,5,6,7}

>>> s2={5,6,7,8,9,10}

>>> s1.difference(s2)

{1, 2, 3, 4}

>>> s2.difference(s1)

{8, 9, 10}

把两个集合的交集部分从集合中移除

Remove all elements of another set from this set.

>>> s1={1,2,3,4,5,6,7}

>>> s2={5,6,7,8,9,10}

>>> s1.difference_update(s2)

>>> print(s1)

{1, 2, 3, 4}

>>> s1={1,2,3,4,5,6,7}

>>> s2={5,6,7,8,9,10}

>>> s2.difference_update(s1)

>>> print(s2)

{8, 9, 10}

从集合中移除一个元素，如果被移除的元素不在集合中，不会报错

Remove an element from a set if it is a member.

If the element is not a member, do nothing.

{1, 2, 3, 4, 5, 6, 7}

>>> s1.discard(7)

>>> print(s1)

{1, 2, 3, 4, 5, 6}

>>> s1.discard(4)

>>> print(s1)

{1, 2, 3, 5, 6}

>>> print(s1)

{1, 2, 3, 5, 6}

求两个或多个集合中的交集

Return the intersection of two sets as a new set.

>>> s1={1,2,3,4,5,6,7}

>>> s2={5,6,7,8,9,10}

>>> s1.intersection(s2)

{5, 6, 7}

>>> s2.intersection(s1)

{5, 6, 7}

把两个集合的交集做为新的集合

Update a set with the intersection of itself and another.

>>> s1={1,2,3,4,5,6,7}

>>> s2={5,6,7,8,9,10}

>>> s1.intersection_update(s2)

>>> print(s1)

{5, 6, 7}

>>> print(s2)

{5, 6, 7, 8, 9, 10}

>>> s1={1,2,3,4,5,6,7}

>>> s2={5,6,7,8,9,10}

>>> s2.intersection_update(s1)

>>> print(s2)

{5, 6, 7}

>>> print(s1)

{1, 2, 3, 4, 5, 6, 7}

>>> s1={1,2,3,4,5,6,7}

>>> s2={5,6,7,8,9,10}

>>> s1.isdisjoint(s2)

False

>>> s1={1,2,3,4}

>>> s2={6,7,8,9}

>>> s1.isdisjoint(s2)

True

如果本集合是参数集合的子集，返回True

Report whether another set contains this set.

>>> s1={1,2,3,4}

>>> s2={1,2,3,4,5,6,7}

>>> s1.issubset(s2)

True

>>> s2.issubset(s1)

False

如果本集合是参数集合的超集，返回True

Report whether this set contains another set.

>>> s1={1,2,3,4}

>>> s2={1,2,3,4,5,6,7}

>>> s1.issuperset(s2)

False

>>> s2.issuperset(s1)

True

从集合中移除一个元素，如果集合为空，则报错

Remove and return an arbitrary set element.

Raises KeyError if the set is empty.

>>> s1={2,3,4,5}

>>> s1.pop()

2

>>> print(s1)

{3, 4, 5}

>>> s1.pop()

3

>>> s1.pop()

4

>>> s1.pop()

5

>>> s1.pop()

Traceback (most recent call last):

  File "<stdin>", line 1, in <module>

KeyError: 'pop from an empty set'

移除集合中的一个元素，如果集合是空的，则报错

Remove an element from a set; it must be a member. 

If the element is not a member, raise a KeyError.

>>> s1={1,2,3,4,5,6}

>>> s1.remove(4)

>>> print(s1)

{1, 2, 3, 5, 6}

>>> s1.remove(9)

Traceback (most recent call last):

  File "<stdin>", line 1, in <module>

KeyError: 9

返回两个集合的对称差集的集合

Return the symmetric difference of two sets as a new set.

>>> s1={1,2,3,4}

>>> s2={6,7,8,9}

>>> s1.symmetric_difference(s2)

{1, 2, 3, 4, 6, 7, 8, 9}

>>> s3={1,2,3,4,5,6}

>>> s4={5,6,7,8,9,10}

>>> s3.symmetric_difference(s4)

{1, 2, 3, 4, 7, 8, 9, 10}

与参数集合做对称差集，并返回给自身

Update a set with the symmetric difference of itself and another.

>>> s1={1,2,3,4}

>>> s2={6,7,8,9}

>>> s2.symmetric_difference_update(s1)

>>> print(s2)

{1, 2, 3, 4, 6, 7, 8, 9}

>>> s3={1,2,3,4,5,6}

>>> s4={5,6,7,8,9,10}

>>> s3.symmetric_difference_update(s4)

>>> print(s3)

{1, 2, 3, 4, 7, 8, 9, 10}

求两个或多个集合的并集

Return the union of sets as a new set.

>>> s1={1,2,3,4,5,6}

>>> s2={5,6,7,8,9}

>>> s1.union(s2)

{1, 2, 3, 4, 5, 6, 7, 8, 9}

>>> s3={1,2,3,4}

>>> s4={6,7,8,9}

>>> s3.union(s4)

{1, 2, 3, 4, 6, 7, 8, 9}

与另一个集合求并集，并返回给自身

Update a set with the union of itself and others.

>>> s3={1,2,3,4}

>>> s4={6,7,8,9}

>>> s3.update(s4)

>>> print(s3)

{1, 2, 3, 4, 6, 7, 8, 9}