python 集合(set)基础

1、定义

list_1 = [1,4,5,7,3,6,7,9]
list_1 = set(list_1)
list_2 =set([2,6,0,66,22,8,4])
print(list_1,list_2)

　　打印输出结果：

{1, 3, 4, 5, 6, 7, 9} {0, 2, 66, 4, 6, 8, 22}

2、交集

list_1 = [1,4,5,7,3,6,7,9]
list_1 = set(list_1)
list_2 =set([2,6,0,66,22,8,4])

print(  list_1.intersection(list_2) )
print(list_1 & list_2)

　　打印输出结果：

{4, 6}
{4, 6}

3、并集

list_1 = [1,4,5,7,3,6,7,9]
list_1 = set(list_1)
list_2 =set([2,6,0,66,22,8,4])

print(list_1.union(list_2))
print(list_1 | list_2)

 　　打印输出结果：

{0, 1, 2, 3, 4, 5, 6, 7, 66, 9, 8, 22}
{0, 1, 2, 3, 4, 5, 6, 7, 66, 9, 8, 22}

4、 差集 in list_1 but not in list_2

list_1 = [1,4,5,7,3,6,7,9]
list_1 = set(list_1)
list_2 =set([2,6,0,66,22,8,4])

print(list_1.difference(list_2))
print(list_1 - list_2)

　　打印输出结果：

{1, 3, 5, 7, 9}
{1, 3, 5, 7, 9}

5、差集 in list_2 but not in list_1

list_1 = [1,4,5,7,3,6,7,9]
list_1 = set(list_1)
list_2 =set([2,6,0,66,22,8,4])

print(list_2.difference(list_1))
print(list_2 - list_1)

　　打印输出结果：

{0, 2, 66, 8, 22}
{0, 2, 66, 8, 22}

6、子集

list_1 = [1,4,5,7,3,6,7,9]
list_1 = set(list_1)
list_3 = set([1,3,7])

print(list_3.issubset(list_1))

　　打印输出结果：

True

7、超集

list_1 = [1,4,5,7,3,6,7,9]
list_1 = set(list_1)
list_3 = set([1,3,7])

print(list_1.issuperset(list_3))

　　打印输出结果：

True

8、对称差集

list_1 = [1,4,5,7,3,6,7,9]
list_1 = set(list_1)
list_2 =set([2,6,0,66,22,8,4])

print(list_1.symmetric_difference(list_2))
print(list_1 ^ list_2)

　　打印输出结果：

{0, 1, 2, 66, 3, 5, 7, 8, 9, 22}
{0, 1, 2, 66, 3, 5, 7, 8, 9, 22}

9、判断是否有相同项，没有则返回true

list_3 = set([1,3,7])
list_4 = set([5,6,7,8])
print(list_3.isdisjoint(list_4))

　　打印输出结果：

False

10、add()与update

list_1 = [1,4,5,7,3,6,7,9]
list_1 = set(list_1)

list_1.add(999)
list_1.update([888, 777, 555])
print(list_1)

 　　打印输出结果：

{1, 3, 4, 5, 6, 7, 999, 9, 777, 555, 888}

11、pop()

list_1 = [1,4,5,7,3,6,7,9]
list_1 = set(list_1)

print(list_1.pop())
print(list_1.pop())
print(list_1.pop())
print(list_1.pop())
print(list_1)

　　打印输出结果：

1
3
4
5
{6, 7, 9}

12、discard()

list_1 = [1,4,5,7,3,6,7,9,888]
list_1 = set(list_1)

print(  list_1.discard(888)  )
print(list_1)

　　打印输出结果：

None
{1, 3, 4, 5, 6, 7, 9}