set集合

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    集合,我们在高中的时候专门学习过集合,并集,交集,差集等,下面来看一下集合的定义,如下:

    集合(简称集)是数学中一个基本概念,它是集合论的研究对象,集合论的基本理论直到19世纪才被创立。最简单的说法,即是在最原始的集合论

——朴素集合论中的定义,集合就是“确定的一堆东西”。集合里的“东西”,叫作元素。

    由一个或多个确定的元素所构成的整体叫做集合。若x是集合A元素,则记作xA。集合中的元素有三个特征:1.确定性(集合中的元素必须是

确定的) 2.互异性(集合中的元素互不相同。例如:集合A={1,a},则a不能等于1) 3.无序性(集合中的元素没有先后之分),如集合{3,4,5}和

{3,5,4}算作同一个集合。

特性

    确定性   

  给定一个集合,任给一个元素,该元素或者属于或者不属于该集合,二者必居其一,不允许有模棱两可的情况出现。

    互异性

    一个集合中,任何两个元素都认为是不相同的,即每个元素只能出现一次。有时需要对同一元素出现多次的情形进行刻画,可以使用多重集,其中的元素允许出现多次。

    无序性

    一个集合中每个元素的地位都是相同的,元素之间是无序的。集合上可以定义序关系,定义了序关系后,元素之间就可以按照序关系排序。但就集合本身的特性而言,元素之间没有必然的序。

    由于集合不是特别常用的功能,因此在Python中创建集合的方法只有一种:

    s1 = set()

    1.add(self,*args,**kwargs)

    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

    add(self,*args,**args)是向列表中添加元素,由于列表中的元素是唯一的,下面我们来验证一下:

    >>> s1 = set()
  >>> s1.add("alex")             (1)
  >>> s1
  {‘alex‘}
  >>> s1.add("alex")             (2)
  >>> s1
  {‘alex‘}
  >>> s1.add("sb")               (3)
  >>> s1
  {‘alex‘, ‘sb‘}
    上述代码中,在(1)处,我们向集合s1中添加元素"alex",打印s1,输出alex;接着我们又向集合中添加元素"alex",然后打印列表s1,输出只有"alex",这就是由于列表的唯一性;在(3)处我们输入了一个不一样的元素,然后打印,在列表中存在这个元素。说明列表中的元素是唯一的。
    2.clear(self,*args,**kwargs)

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

    clear(self)是清除集合中所有的元素,清除集合中所有元素,实例如下:

    >>> s1 = {‘alex‘, ‘sb‘}
  >>> s1.clear()
  >>> s1
  set()

    当集合中没有元素的时候,显示的是set(),这样避免让我们觉得这是一个空的字典,区分字典。

    3.copy(self,*args,**kwargs)

    def copy(self, *args, **kwargs): # real signature unknown
    """ Return a shallow copy of a set. """
    pass
    copy(self,*args,**kwargs)复制集合中的元素,产生新的一个内存地址,否则清除集合的时候,关联的其他变量也会被清除掉。实例如下:

    >>> s1 = {‘marry‘, ‘alex‘, ‘aoi‘, ‘sb‘}
  >>> s2 = s1
  >>> s2
  {‘marry‘, ‘alex‘, ‘aoi‘, ‘sb‘}
  >>> s3 = s1.copy()
  >>> s3
  {‘marry‘, ‘alex‘, ‘aoi‘, ‘sb‘}
  >>> s2.clear()
  >>> s1
  set()
  >>> s2
  set()
  >>> s3
  {‘marry‘, ‘alex‘, ‘aoi‘, ‘sb‘}

    从上面代码可以看出,当我们使用赋值关联集合的时候,如果使用等号(=)直接关联,那么使用clear()清除集合的元素的时候,关联的集合中的元素也会被删除,而我们使用copy()就不会出现这样的情况,copy()是在Python内存中重新开辟一个新的内存来存储这个集合。不是直接的关联。

    4.difference(self,*args,**kwargs)

    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

    返回N个集合中不同的元素,形成一个新的集合,
    >>> s1 = {‘zeng‘, ‘alex‘, ‘aoi‘, ‘geng‘}
  >>> s3 = {‘marry‘, ‘alex‘, ‘aoi‘, ‘sb‘}
  >>> s2 = s1.difference(s3)
  >>> s2
  {‘geng‘, ‘zeng‘}

    5.difference_update(self,*args,**kwargs)

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

    difference_update(self,*args,**kwargs)s1.difference_update(s3)从集合s1中删除与s3集合中相同的元素。改变了集合s1,而difference()是生成一个新的集合,两者的结果是一样的,difference_update()是更新了集合s1,而difference()是新生成了一个集合,不改变原来的集合。

    >>> s1 = {‘zeng‘, ‘alex‘, ‘aoi‘, ‘geng‘}
  >>> s3
  {‘marry‘, ‘alex‘, ‘aoi‘, ‘sb‘}
  >>> s1.difference_update(s3)
  >>> s1
  {‘zeng‘, ‘geng‘}
  >>> s3
  {‘marry‘, ‘alex‘, ‘aoi‘, ‘sb‘}

    6.discard(self,*args,**kwargs)

    def discard(self, *args, **kwargs): # real signature unknown
    """
    Remove an element from a set if it is a member.(移除元素)

    If the element is not a member, do nothing.
    """
    pass

    discard(self,*args,**kwargs)移除集合中的元素,如果这个元素不存在集合中,那么什么都不做。实例如下:

  >>> s3 = {‘marry‘, ‘alex‘, ‘aoi‘, ‘sb‘}
  >>> s3.discard("alex")
  >>> s3
  {‘marry‘, ‘aoi‘, ‘sb‘}
  >>> s3.discard("tom")
  >>> s3
  {‘marry‘, ‘aoi‘, ‘sb‘}

    7.intersection(self,*args,**kwargs)

    def intersection(self, *args, **kwargs): # real signature unknown
    """
    Return the intersection of two sets as a new set.(取交集,创建一个新的集合存放交集)

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

  >>> s1 = {‘zeng‘, ‘geng‘, ‘alex‘, ‘sb‘}
  >>> s3 = {‘marry‘, ‘aoi‘, ‘sb‘}
  >>> s1.intersection(s3)
  {‘sb‘}

    s1.intersection(s3)取集合s1和集合s3的交集,返回一个新的集合,不修改原来的集合,intersection_update()取两个集合的交集并修改原来的集合。

  8.intersection_update(self,*args,**kwargs)

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

    >>> s1 = {‘zeng‘, ‘geng‘, ‘alex‘, ‘sb‘}
  >>> s3 = {‘marry‘, ‘aoi‘, ‘sb‘}
  >>> s1.intersection_update(s3)
  >>> s1
  {‘sb‘}
  >>> s3
  {‘marry‘, ‘aoi‘, ‘sb‘}

    s1.intersection_update(s3)取集合s1和集合s3的交集,并把生成的交集元素放到集合s1中,删除两者不是集合的元素。如果两者没有交集则生成一个空的集合。
  9.isdisjoint(self,*args,**kwargs)

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

        """判断是否有交集,如果没有交集,返回True.
      pass
 

    isdisjoint(self,*args,**kwargs)判断集合是否有交集,如果没有交集则返回True。如下所示:

    >>> s4 = set(["alex"])
  >>> s5 = set(["sb"])
  >>> s4.isdisjoint(s5)
  True

    10.issubset(self,*args,**kwargs)

    def issubset(self, *args, **kwargs): # real signature unknown
    """
Report whether another set contains this set. """

        """判断集合是否是指定集合的子集"""
    pass

    issubset(self,*args,**kwargs)判断一个集合是否是另外一个集合的子集。实例如下:

    >>> s1 = set(("alex","sb","tom","divd"))
  >>> s2 = set(("alex","sb"))
  >>> s1.issubset(s2)
  False
  >>> s2.issubset(s1)
  True
    s1.issubset(s2)判断集合s1是否是集合s2的子集,如果是,则返回True。

  11.issuperset(self,*args,**kwargs)

    def issuperset(self, *args, **kwargs): # real signature unknown
    """
Report whether this set contains another set.
"""

        """判断是否是父集"""
    pass

    issuperset(self,*args,**kwargs)判断是否是父集,即s1.issuperset(s2)是判断集合s1包含集合s2,跟issubset()相反,实例如下:

  >>> s1 = set(("alex","sb","tom","divd"))
  >>> s2 = set(("alex","sb"))

    >>> s1.issuperset(s2)
  True
  >>> s2.issuperset(s1)
  False

    12.pop(self,*args,**kwargs)

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

    pop(self)从集合中弹出一个元素,并赋值给另外一个变量,实例如下:

    >>> s1 = {‘going‘, ‘tom‘, ‘alex‘, ‘is‘, ‘sb‘}
  >>> s1.pop()
  ‘alex‘
  >>> s1
  {‘going‘, ‘tom‘, ‘is‘, ‘sb‘}
    pop(self)不需要参数,表示的是从集合中移除一个元素,并赋值给一个新的变量,移除元素赋值,弹出,不想remove()是从集合中删除元素没有返回值。

    13.remove(self,*args,**kwargs)

    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

    remove(self,member)从集合中移除元素,没有返回值,删除集合中的值,remove(menber),实例如下:

    >>> s1 = {‘going‘, ‘tom‘, ‘is‘, ‘sb‘}
    >>> s1.remove("is")
  >>> s1
  {‘going‘, ‘tom‘, ‘sb‘}
    remove(menber)是从集合中移除元素,而pop()是从集合中弹出一个元素并赋值给新的变量。两者的区别在于,一个有返回值可以利用,而另外一个是没有返回值的。

    14.symmertric_difference(self,*args,**kwargs)

    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

  symmertric_difference(self,*args,**kwargs)返回两个集合的差集,实例如下:

    >>> s1 = {‘going‘, ‘tom‘, ‘sb‘}
  >>> s2 = set(("tom","Alex"))
  >>> s1.symmetric_difference(s2)
  {‘going‘, ‘Alex‘, ‘sb‘}
    s1.symmetric_difference(s2)返回两个集合的差集,即两个集合交集减去重叠的部分。

    15.symmertic_difference_update(self,*args,**kwargs)

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

    >>> s1 = {‘going‘, ‘tom‘, ‘sb‘}
  >>> s2 = {‘tom‘, ‘Alex‘}
  >>> s1.symmetric_difference_update(s2)
  >>> s1
  {‘going‘, ‘Alex‘, ‘sb‘}
  >>> s2
  {‘tom‘, ‘Alex‘}

    返回两个集合的差集。

    16.union(self,*args,**kwargs)

    def union(self, *args, **kwargs): # real signature unknown
    """
    Return the union of sets as a new set.(并集)

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

    union(self,*args,**kwargs)两个集合的并集,如下:

    >>> s1 = {‘going‘, ‘Alex‘, ‘sb‘}
  >>> s2 = {‘tom‘, ‘Alex‘}
  >>> s1.union(s2)
  {‘going‘, ‘tom‘, ‘Alex‘, ‘sb‘}

    17.update(self,*args,**kwargs)

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

    18.__and__(self,*args,**kwargs)

    def __and__(self, *args, **kwargs): # real signature unknown
    """ Return self&value. """
    pass

    19.__contains__(self,y)

    def __contains__(self, y): # real signature unknown; restored from __doc__
    """
x.__contains__(y) <==> y in x. """
    pass

    20.__getattribute__(self,*args,**kwargs)

    def __getattribute__(self, *args, **kwargs): # real signature unknown
    """ Return getattr(self, name). """
    pass

    21.__iand__(self,*args,**kwargs)

    def __iand__(self, *args, **kwargs): # real signature unknown
    """ Return self&=value. """
    pass

    22.__ior__(self,*args,**kwargs)

    def __ior__(self, *args, **kwargs): # real signature unknown
    """ Return self|=value. """
    pass

    23.__isub__(self,*args,**kwargs)

    def __isub__(self, *args, **kwargs): # real signature unknown
    """
Return self-=value. """
    pass

    24.__iter__(self,*args,**kwargs)

    def __iter__(self, *args, **kwargs): # real signature unknown
    """ Implement iter(self). """
    pass

    25.__ixor__(self,*args,**kwargs)

    def __ixor__(self, *args, **kwargs): # real signature unknown
    """ Return self^=value. """
    pass

    26.__len__(self,*args,**kwargs)

    def __len__(self, *args, **kwargs): # real signature unknown
    """ Return len(self). """
    pass

    27.__new__(*args,**kwargs)

    def __new__(*args, **kwargs): # real signature unknown
    """ Create and return a new object. See help(type) for accurate signature. """
    pass

    28.__or__(self,*args,**kwargs)

    def __or__(self, *args, **kwargs): # real signature unknown
    """ Return self|value. """
    pass

    29.__rand__(self,*args,**kwargs)

    def __rand__(self, *args, **kwargs): # real signature unknown
    """ Return value&self. """
    pass

    30.__reduce__(self,*args,**kwargs)

    def __reduce__(self, *args, **kwargs): # real signature unknown
    """ Return state information for pickling. """
    pass

    31.__repr__(self,*args,**kwargs)

    def __repr__(self, *args, **kwargs): # real signature unknown
    """ Return repr(self). """
    pass

    32.__ror__(self,*args,**kwargs)

    def __ror__(self, *args, **kwargs): # real signature unknown
    """ Return value|self. """
    pass

    33.__rsub__(self,*args,**kwargs)

    def __rsub__(self, *args, **kwargs): # real signature unknown
    """ Return value-self. """
    pass

    34.__rxor__(self,*args,**kwargs)

    def __rxor__(self, *args, **kwargs): # real signature unknown
    """ Return value^self. """
    pass

    35.__sizeof__(self)

    def __sizeof__(self): # real signature unknown; restored from __doc__
    """ S.__sizeof__() -> size of S in memory, in bytes """
    pass

    36.__sub__(self,*args,**kwargs)

    def __sub__(self, *args, **kwargs): # real signature unknown
    """ Return self-value. """
    pass

    37.__xor__(self,*args,**kwargs)

    def __xor__(self, *args, **kwargs): # real signature unknown
    """ Return self^value. """
    pass

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