python笔记 - 集合set（九）_set1={2,3,5}

无序不重复序列，可使用{}或set()函数创建集合，空集合只能使用set()
集合中元素只能是字符串、数字、元组

1、创建集合

{value1, value2,...} 或 set(value)

>>> set1 = {'apple', 'orange', 'apple', 'banana'}
>>> set1
{'orange', 'apple', 'banana'}
>>> set1 = set({'apple', 'orange', 'apple', 'banana'})
>>> set1
{'orange', 'apple', 'banana'}
>>> type(set())
<class 'set'>
>>> type({})
<class 'dict'>
1
2
3
4
5
6
7
8
9
10

2、返回两个集合交集(intersection)

set1.intersection(set2)

>>> set1 = {'apple', 'orange'}
>>> set2 = {'orange', 'banana'}
>>> set1.intersection(set2)
{'orange'}
1
2
3
4

3、返回两个集合并集(union)

set1.union(set2)

>>> set1 = {'apple', 'orange'}
>>> set2 = {'orange', 'banana'}
>>> set1.union(set2)
{'orange', 'apple', 'banana'}
1
2
3
4

4、做差

set1.difference(set2) set1中不同于set2中的元素

>>> set1 = {'apple', 'orange'}
>>> set2 = {'orange', 'banana'}
>>> set1.difference(set2)
{'apple'}
1
2
3
4

5、去重(symmetric_difference)

set1.symmetric_difference(set2) 并集去除重复

>>> set1 = {'apple', 'orange'}
>>> set2 = {'orange', 'banana'}
>>> set1.symmetric_difference(set2)
{'apple', 'banana'}
1
2
3
4

6、添加元素(add)

set.add(obj) obj为不可变数据类型

>>> set1 = {'apple', 'orange'}
>>> set1.add(1)
>>> set1.add('banbana')
>>> set1.add((1, 3, 4))
>>> set1
{1, 'banbana', 'apple', (1, 3, 4), 'orange'}
>>> set1.add([1, 3])
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: unhashable type: 'list'
>>> set1.add({'k':'v'})
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: unhashable type: 'dict'
>>> set1.add({1, 3})
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: unhashable type: 'set'
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18

7、添加元素(update)

set.update(obj) obj为可迭代对象，字符串是单个字符作为元素添加，其他数据结构单个元素添加

>>> set1 = {'apple', 'orange'}
>>> set1.update('chinese')
>>> set1
{'apple', 'h', 'n', 'c', 's', 'orange', 'i', 'e'}
>>> set1.update(["banana", 'grape'])
>>> set1
{'apple', 'banana', 'h', 'n', 'c', 's', 'grape', 'orange', 'i', 'e'}
>>> set1.update(["joker", '95'])
>>> set1
{'apple', 'banana', 'h', 'n', 'c', '95', 's', 'grape', 'orange', 'i', 'e', 'joker'}
1
2
3
4
5
6
7
8
9
10

8、随机移除元素，并返回该元素

set.pop()

>>> set1 = {'apple', 'orange', 'grape', 'banbana'}
>>> set1.pop()
'grape'
>>> set1
{'orange', 'apple', 'banbana'}
>>> set1.pop()
'orange'
>>> set1
{'apple', 'banbana'}
1
2
3
4
5
6
7
8
9

9、移除指定元素(remove)

set.remove(value) 不存在报错

>>> set1 = {'apple', 'orange', 'grape', 'banbana'}
>>> set1.remove('apple')
>>> set1
{'grape', 'orange', 'banbana'}
>>> set1.remove('apple')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
KeyError: 'apple'
1
2
3
4
5
6
7
8

10、移除指定元素(discard)

set.discard(value) 不存在不作操作

>>> set1 = {'apple', 'orange', 'grape', 'banbana'}
>>> set1.discard('apple')
>>> set1
{'grape', 'orange', 'banbana'}
>>> set1.discard('apple')
>>>
1
2
3
4
5
6

11、清空集合中元素

set.clear()

>>> set1 = {'apple', 'orange', 'grape', 'banbana'}
>>> set1.clear()
>>> set1
set()
1
2
3
4

12、判断两个集合是否不相交

set1.isdisjoint(set2) 不相交返回True，相交返回False

>>> set1 = {1, 3, 5}
>>> set2 = {3, 5, 7}
>>> set1.isdisjoint(set2)
False
1
2
3
4

13、判断当前集合是否为指定集合的子集

set1.issubset(set2)

>>> set1 = {3, 5}
>>> set2 = {1, 3, 5}
>>> set1.issubset(set2)
True
1
2
3
4

14、判断当前集合是否为指定集合的超(父)集

set1.issuperset(set2)

>>> set1 = {1, 3, 5}
>>> set2 = {3, 5}
>>> set1.issuperset(set2)
True
1
2
3
4