# 集合类型内置方法

## 一、集合类型内置方法(set)

``````pythoners = ['jason', 'nick', 'tank', 'sean']
linuxers = ['nick', 'egon', 'kevin']

# 即报名pythoners又报名linux的学生
py_li_list = []
for stu in pythoners:
if stu in linuxers:
py_li_list.append(stu)
print(f"pythoners and linuxers: {py_li_list}")``````
``pythoners and linuxers: ['nick']``

1.用途：用于关系运算的集合体，由于集合内的元素无序且集合元素不可重复，因此集合可以去重，但是去重后的集合会打乱原来元素的顺序。

2.定义：{}内用逗号分隔开多个元素，每个元素必须是不可变类型。

``````s = {1, 2, 1, 'a'}  # s = set({1,2,'a'})

print(f"s: {s}")``````
``s: {1, 2, 'a'}``
``````s = {1, 2, 1, 'a', 'c'}

for i in s:
print(i)``````
``````1
2
c
a``````
``````s = set('hello')

print(f"s: {s}")``````
``s: {'e', 'o', 'h', 'l'}``

3.常用操作+内置方法：常用操作和内置方法分为优先掌握（今天必须得记住）、需要掌握（一周内记住）两个部分。

### 1.1 优先掌握(*****)

• 长度len
• 成员运算in和not in
• |并集、union
• &交集、intersection
• -差集、difference
• ^对称差集、symmetric_difference
• ==
• 父集：>、>= 、issuperset
• 子集：<、<= 、issubset

1.长度len

``````# set之长度len
s = {1, 2, 'a'}

print(f"len(s): {len(s)}")``````
``len(s): 3``

2.成员运算in和not in

``````# set之成员运算in和not in
s = {1, 2, 'a'}

print(f"1 in s: {1 in s}")``````
``1 in s: True``

3.|并集

``````# str之|并集
pythoners = {'jason', 'nick', 'tank', 'sean'}
linuxers = {'nick', 'egon', 'kevin'}

print(f"pythoners|linuxers: {pythoners|linuxers}")
print(f"pythoners.union(linuxers): {pythoners.union(linuxers)}")``````
``````pythoners|linuxers: {'egon', 'tank', 'kevin', 'jason', 'nick', 'sean'}
pythoners.union(linuxers): {'egon', 'tank', 'kevin', 'jason', 'nick', 'sean'}``````

4.&交集

``````# str之&amp;交集
pythoners = {'jason', 'nick', 'tank', 'sean'}
linuxers = {'nick', 'egon', 'kevin'}

print(f"pythoners&amp;linuxers: {pythoners&amp;linuxers}")
print(f"pythoners.intersection(linuxers): {pythoners.intersection(linuxers)}")``````
``````pythoners&amp;linuxers: {'nick'}
pythoners.intersection(linuxers): {'nick'}``````

5.-差集

``````# str之-差集
pythoners = {'jason', 'nick', 'tank', 'sean'}
linuxers = {'nick', 'egon', 'kevin'}

print(f"pythoners-linuxers: {pythoners-linuxers}")
print(f"pythoners.difference(linuxers): {pythoners.difference(linuxers)}")``````
``````pythoners-linuxers: {'tank', 'jason', 'sean'}
pythoners.difference(linuxers): {'tank', 'jason', 'sean'}``````

6.^对称差集

``````# str之^对称差集
pythoners = {'jason', 'nick', 'tank', 'sean'}
linuxers = {'nick', 'egon', 'kevin'}

print(f"pythoners^linuxers: {pythoners^linuxers}")
print(
f"pythoners.symmetric_difference(linuxers): {pythoners.symmetric_difference(linuxers)}")``````
``````pythoners^linuxers: {'egon', 'tank', 'kevin', 'jason', 'sean'}
pythoners.symmetric_difference(linuxers): {'egon', 'tank', 'kevin', 'jason', 'sean'}``````

7.==

``````# str之==
pythoners = {'jason', 'nick', 'tank', 'sean'}
linuxers = {'nick', 'egon', 'kevin'}
javers = {'nick', 'egon', 'kevin'}

print(f"pythoners==linuxers: {pythoners==linuxers}")
print(f"javers==linuxers: {javers==linuxers}")``````
``````pythoners==linuxers: False
javers==linuxers: True``````

8.父集：>、>=

``````# str之父集：>、>=
pythoners = {'jason', 'nick', 'tank', 'sean'}
linuxers = {'nick', 'egon', 'kevin'}
javaers = {'jason', 'nick'}

print(f"pythoners>linuxers: {pythoners>linuxers}")
print(f"pythoners>=linuxers: {pythoners>=linuxers}")
print(f"pythoners>=javaers: {pythoners>=javaers}")
print(f"pythoners.issuperset(javaers): {pythoners.issuperset(javaers)}")``````
``````pythoners>linuxers: False
pythoners>=linuxers: False
pythoners>=javaers: True
pythoners.issuperset(javaers): True``````

9.子集：<、<=

``````# str之子集：<、<=
pythoners = {'jason', 'nick', 'tank', 'sean'}
linuxers = {'nick', 'egon', 'kevin'}
javaers = {'jason', 'nick'}

print(f"pythoners<linuxers: {pythoners<linuxers}")
print(f"pythoners<=linuxers: {pythoners<=linuxers}")
print(f"javaers.issubset(javaers): {javaers.issubset(javaers)}")``````
``````pythoners<linuxers: False
pythoners<=linuxers: False
javaers.issubset(javaers): True``````

### 1.2 需要掌握(****)

• remove
• difference_update
• isdisjoint

``````# set之add()
s = {1, 2, 'a'}

print(s)``````
``{1, 2, 3, 'a'}``

2.remove()

``````# set之remove()
s = {1, 2, 'a'}
s.remove(1)

print(s)``````
``{2, 'a'}``

3.difference_update()

``````# str之difference_update()
pythoners = {'jason', 'nick', 'tank', 'sean'}
linuxers = {'nick', 'egon', 'kevin'}
pythoners.difference_update(linuxers)

print(f"pythoners.difference_update(linuxers): {pythoners}")``````
``pythoners.difference_update(linuxers): {'tank', 'jason', 'sean'}``

``````# set之discard()
s = {1, 2, 'a'}
# s.remove(3)  # 报错

print(s)``````
``{1, 2, 'a'}``

5.isdisjoint()

``````# set之isdisjoint()，集合没有共同的部分返回True，否则返回False
pythoners = {'jason', 'nick', 'tank', 'sean'}
linuxers = {'nick', 'egon', 'kevin'}
pythoners.isdisjoint(linuxers)

print(f"pythoners.isdisjoint(linuxers): {pythoners.isdisjoint(linuxers)}")``````
``pythoners.isdisjoint(linuxers): False``

## 二、练习

``````stu_info_list = [
{'name':'nick','age':19,'sex':'male'},
{'name':'egon','age':18,'sex':'male'},
{'name':'tank','age':20,'sex':'female'},
{'name':'tank','age':20,'sex':'female'},
{'name':'egon','age':18,'sex':'male'},
]``````
``````stu_info_list = [
{'name': 'nick', 'age': 19, 'sex': 'male'},
{'name': 'egon', 'age': 18, 'sex': 'male'},
{'name': 'tank', 'age': 20, 'sex': 'female'},
{'name': 'tank', 'age': 20, 'sex': 'female'},
{'name': 'egon', 'age': 18, 'sex': 'male'},
]

new_stu_info_list = []
for stu_info in stu_info_list:
if stu_info not in new_stu_info_list:
new_stu_info_list.append(stu_info)

for new_stu_info in new_stu_info_list:
print(new_stu_info)``````
``````{'name': 'nick', 'age': 19, 'sex': 'male'}
{'name': 'egon', 'age': 18, 'sex': 'male'}
{'name': 'tank', 'age': 20, 'sex': 'female'}``````

4.存一个值or多个值：多个值，且值为不可变类型。
5.有序or无序：无序

``````s = {1, 2, 'a'}
print(f'first:{id(s)}')
print(f'second:{id(s)}')``````
``````first:4480523848
second:4480523848``````

6.可变or不可变：可变数据类型

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