python 学习_集合

set
特点：
集合   是一个无序的， 不重复的数据组合，它的主要作用有：
　　  去重      把一个列表变成集合， 就自动去重了
         集合中的元素必须是不可变元素


创建集合

s = {1,2,3,4,5,3,5,1}
print(s)
print(type(s))

#   {1, 2, 3, 4, 5}
#   <class 'set'>

交集

s = {1,2,3,4,5,3,5,1}
ss = {2,3,4}


# &
# intersection()

print("s与ss的交集：     ",s.intersection(ss))
print("s与ss的交集：     ",s&ss)

# s与ss的交集：      {2, 3, 4}
# s与ss的交集：      {2, 3, 4}

并集

s = {1,2,3,4,5,3,5,1}
ss = {2,3,4}

# 并集  等于2个列表去重

# union
#  |

print("s与ss的并集：     ",s.union(ss))
print("s与ss的并集:     ", s|ss  )

# s与ss的并集：      {1, 2, 3, 4, 5}
# s与ss的并集:      {1, 2, 3, 4, 5}

差集

s = {1,2,3,4,5,3,5,1}
ss = {2,3,4}
# difference
#-
print("s与ss的差集： ",s.difference(ss))
print("s与ss的差集： ",s-ss)
# s与ss的差集：  {1, 5}
# s与ss的差集：  {1, 5}

对称差集

s = {1,2,3,4,5,3,5,1}
ss = {2,3,4,333}

#symmetric_difference
#^
print(s.symmetric_difference(ss))
print(s^ss)

# {1, 5, 333}
# {1, 5, 333}

issubset

# #issubset
s = {1,2,3,4,5,3,5,1,333}
ss = {2,3,4,333}

# ss是s的子集
print(ss.issubset(s))
# True

# s 是ss的子集
print(s.issubset(ss))
# False

issuperset

# #issuperset
s = {1,2,3,4,5,3,5,1,333}
ss = {2,3,4,333}

# s 是ss的父集
print(s.issuperset(ss))
# True


# ss是 s的父集
print(ss.issuperset(s))
# False

元素的添加

a = {1,2}
a.update([1,34,5,6,67])  
# update 添加多个元素

a.add("wwww")
# add  添加一个元素
print(a)

元素的删除

discard    存在就删除， 不存在也不报错

s = {1,2,3,4,5,3,5,1,333}
# # 元素的删除
# discard   存在就删除， 不存在 也不报错
s.discard('2ww')
print(s)
# {1, 2, 3, 4, 5, 333}

remove

s = {1,2,3,4,5,3,5,1,333}
s.remove('x')   # 不存在会抛出 KeyError错误

Traceback (most recent call last):
  File "D:/python/luffycity/元组/集合类型.py", line 135, in <module>
    s.remove('x')   # 不存在会抛出 KeyError错误
KeyError: 'x'

元素的源码

class set(object):
    """
    set() -> new empty set object
    set(iterable) -> new set object
    
    Build an unordered collection of unique elements.
    """
    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

    def clear(self, *args, **kwargs): # real signature unknown
        """ Remove all elements from this set. """
        pass

    def copy(self, *args, **kwargs): # real signature unknown
        """ Return a shallow copy of a set. """
        pass

    def difference(self, *args, **kwargs): # real signature unknown
        """
        Return the difference of two or more sets as a new set.
         相当于 s1 - s2   差集  
        (i.e. all elements that are in this set but not the others.)
        """
        pass

    def difference_update(self, *args, **kwargs): # real signature unknown
        """ Remove all elements of another set from this set. """
        pass

    def discard(self, *args, **kwargs): # real signature unknown
        """
        Remove an element from a set if it is a member.
        
        与remove功能相同，删除元素不存在时不会抛出异常
        
        If the element is not a member, do nothing.
        """
        pass

    def intersection(self, *args, **kwargs): # real signature unknown
        """
        Return the intersection of two sets as a new set.
        
        相当于 s1&s2  求交集
        
        (i.e. all elements that are in both sets.)
        """
        pass

    def intersection_update(self, *args, **kwargs): # real signature unknown
        """ Update a set with the intersection of itself and another. """
        pass

    def isdisjoint(self, *args, **kwargs): # real signature unknown
        """ Return True if two sets have a null intersection. """
        pass

    def issubset(self, *args, **kwargs): # real signature unknown
        """ Report whether another set contains this set. 
        
        相当于 s1 <=s2
        """
        pass

    def issuperset(self, *args, **kwargs): # real signature unknown
        """ Report whether this set contains another set. 
        相当于 s1 >=s2
        
        """
        pass

    def pop(self, *args, **kwargs): # real signature unknown
        """
        Remove and return an arbitrary set element.
        Raises KeyError if the set is empty.
        """
        pass

    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

    def symmetric_difference(self, *args, **kwargs): # real signature unknown
        """
        Return the symmetric difference of two sets as a new set.
        
        相当于 s1^s2      对称差集
        
        (i.e. all elements that are in exactly one of the sets.)
        """
        pass

    def symmetric_difference_update(self, *args, **kwargs): # real signature unknown
        """ Update a set with the symmetric difference of itself and another. """
        pass

    def union(self, *args, **kwargs): # real signature unknown
        """
        
        并集   相当于s1|s2 
        
        Return the union of sets as a new set.
        
        (i.e. all elements that are in either set.)
        """
        pass

    def update(self, *args, **kwargs): # real signature unknown
        """ Update a set with the union of itself and others. """
        pass