Python集合常用操作

字典常用的就是，他的去重。

set集合是python的一个基本数据类型.

set中的元素是不重复的.⽆无序的.⾥面的元素必须是可hash的(int, str, tuple,bool)。

我们可以这样来记. set就是dict类型的数据但是不保存value, 只保存key. set也⽤{}表⽰

注意:

set中的元素是不重复的, 且无序的.

使⽤用这个特性.我们可以使⽤用set来去掉重复

set集合中的元素必须是可hash的, 但是set本身是不可hash得. set是可变的。

set集合增删改查

1.增加

def add(self, *args, **kwargs): # real signature unknown

"""

Add an element to a set.

This has no effect if the element is already present.

"""

pass

用法：添加一个元素到集合。重复的内容不会被添加到set集合。

例子：

s = {"刘大哥", '关大哥', "张大哥"}

s.add("赵子龙")

print(s)

s.add("赵子龙") # 重复的内容不不会被添加到set集合中

print(s)

def update(self, *args, **kwargs): # real signature unknown

""" Update a set with the union of itself and others. """

pass

用法：迭代更新

例子：

s = {"刘大哥", '关大哥', "张大哥"}

s.update("赵子龙") # 迭代更更新

print(s)

s.update(["阿斗", "卧龙","凤雏"])

print(s)

2.删除

def pop(self, *args, **kwargs): # real signature unknown

"""

Remove and return an arbitrary set element.

Raises KeyError if the set is empty.

"""

pass

用法：随机删除一个元素，如果集合为空，会报错。

例子：

s = {"刘大哥", '关大哥', "王大哥","张哥哥"}

item = s.pop() # 随机弹出⼀一个.

print(s)

print(item)

def remove(self, *args, **kwargs): # real signature unknown

"""

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

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

"""

pass

用法：删除集合中指定成员，如果成员不存在会报错。

例子：

s = {"刘大哥", '关大哥', "王大哥","张哥哥"}

s.remove("关大哥") # 直接删除元素

# s.remove("⻢马") # 不不存在这个元素. 删除会报错

print(s)

def discard(self, *args, **kwargs): # real signature unknown

"""

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

If the element is not a member, do nothing.

"""

pass

用法：删除集合中指定成员，如果该集合不存在所删除成员，不做任何操作，也不会报错。

例子：

s =

print(s)#

s.discard(3)

print(s)#

s.discard(66)

print(s)#

def clear(self, *args, **kwargs): # real signature unknown

""" Remove all elements from this set. """

pass

clear() 清空set集合。

注意：set集合如果是空的。打印出来的是set()。需要和dict区分。

例子：

s =

s.clear()

print(s)。#set()

3.修改

set 集合中的数据没有索引，也没有办法定位一个元素。所以没有办法直接修改。

我们可以采用：

1）先删除后添加的方式

2）将set转为list删除元素后将list转为set

4.查询

set是一个可迭代对象，所以可以进行for循环

for x in s:

print(x)

5.常用操作

1.求差集（-）

def difference(self, *args, **kwargs): # real signature unknown

"""

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

(i.e. all elements that are in this set but not the others.)

"""

pass

例子：

s1 =

s2 =

print(s1-s2)#

print(s1.difference(s2))#

print(s2-s1)#

print(s2.difference(s1))#

2.求交集（&）

def intersection(self, *args, **kwargs): # real signature unknown

"""

Return the intersection of two sets as a new set.

(i.e. all elements that are in both sets.)

"""

pass

例子：

s1 =

s2 =

print(s1&s2)#

print(s1.intersection(s2))

print(s2&s1)#

print(s2.intersection(s1))

3.求对称差集（^）

def symmetric_difference(self, *args, **kwargs): # real signature unknown

"""

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

(i.e. all elements that are in exactly one of the sets.)

"""

pass

例子：

s1 =

s2 =

print(s1 ^ s2)#

print(s1.symmetric_difference(s2))#

print(s2 ^ s1)#

print(s2.symmetric_difference(s1))#

4.求并集（|）

def union(self, *args, **kwargs): # real signature unknown

"""

Return the union of sets as a new set.

(i.e. all elements that are in either set.)

"""

pass

例子：

s1 =

s2 =

print(s1 | s2)#

print(s1.union(s2))#

print(s2 | s1)#

print(s2.union(s1))#

5.子集

def issubset(self, *args, **kwargs): # real signature unknown

""" Report whether another set contains this set. """

pass

例子：

s1 = {"1", "2"}

s2 = {"1", "2", "3"}

# ⼦子集

print(s1

print(s1.issubset(s2))

6.超集

def issuperset(self, *args, **kwargs): # real signature unknown

""" Report whether this set contains another set. """

pass

例子：

s1 = {"1", "2"}

s2 = {"1", "2", "3"}

print(s1 > s2) # set1是set2的超集吗? False

print(s1.issuperset(s2))