014-python基础-set集合

集合是一个无序的，不重复的数据组合，它的主要作用如下：

• 去重，把一个列表变成集合，就自动去重了
• 关系测试，测试两组数据之前的交集、差集、并集等关系

注：作为一个无序的集合，sets不记录元素位置或者插入点。因此sets不支持indexing，slicing(切片）

  1 class set(object):
  2     """
  3     set() -> new empty set object
  4     set(iterable) -> new set object
  5
  6     Build an unordered collection of unique elements.
  7     """
  8     def add(self, *args, **kwargs): # real signature unknown
  9         """
 10         Add an element to a set.     #添加元素
 11
 12         This has no effect if the element is already present.
 13         """
 14         pass
 15
 16     def clear(self, *args, **kwargs): # real signature unknown
 17         """ Remove all elements from this set. """     #清除所有元素
 18         pass
 19
 20     def copy(self, *args, **kwargs): # real signature unknown
 21         """ Return a shallow copy of a set. """            #浅拷贝
 22         pass
 23
 24     def difference(self, *args, **kwargs): # real signature unknown
 25         """
 26         Return the difference of two or more sets as a new set.    #a中存在，b中不存在
 27
 28         (i.e. all elements that are in this set but not the others.)
 29         """
 30         pass
 31
 32     def difference_update(self, *args, **kwargs): # real signature unknown
 33         """ Remove all elements of another set from this set. 从当前集合中删除和B中相同的元素"""
 34         pass
 35
 36     def discard(self, *args, **kwargs): # real signature unknown
 37         """
 38         Remove an element from a set if it is a member.    移除指定元素，不存在不报错
 39
 40         If the element is not a member, do nothing.
 41         """
 42         pass
 43
 44     def intersection(self, *args, **kwargs): # real signature unknown
 45         """
 46         Return the intersection of two sets as a new set.   交集
 47
 48         (i.e. all elements that are in both sets.)
 49         """
 50         pass
 51
 52     def intersection_update(self, *args, **kwargs): # real signature unknown
 53         """ Update a set with the intersection of itself and another.   取交集并更新到a中 """
 54         pass
 55
 56     def isdisjoint(self, *args, **kwargs): # real signature unknown
 57         """ Return True if two sets have a null intersection. 如果没有交集，返回True """
 58         pass
 59
 60     def issubset(self, *args, **kwargs): # real signature unknown
 61         """ Report whether another set contains this set. 是否是子序列  """
 62         pass
 63
 64     def issuperset(self, *args, **kwargs): # real signature unknown
 65         """ Report whether this set contains another set.   是否是父序列"""
 66         pass
 67
 68     def pop(self, *args, **kwargs): # real signature unknown
 69         """
 70         Remove and return an arbitrary set element.  移除元素
 71         Raises KeyError if the set is empty.
 72         """
 73         pass
 74
 75     def remove(self, *args, **kwargs): # real signature unknown
 76         """
 77         Remove an element from a set; it must be a member.   移除指定元素，不存在保错
 78
 79         If the element is not a member, raise a KeyError.
 80         """
 81         pass
 82
 83     def symmetric_difference(self, *args, **kwargs): # real signature unknown
 84         """
 85         Return the symmetric difference of two sets as a new set.   对称差集，a有b没有 + b有a没有
 86
 87         (i.e. all elements that are in exactly one of the sets.)
 88         """
 89         pass
 90
 91     def symmetric_difference_update(self, *args, **kwargs): # real signature unknown
 92         """ Update a set with the symmetric difference of itself and another. """   对称差集，并更新到a中
 93         pass
 94
 95     def union(self, *args, **kwargs): # real signature unknown
 96         """
 97         Return the union of sets as a new set.             并集
 98
 99         (i.e. all elements that are in either set.)
100         """
101         pass
102
103     def update(self, *args, **kwargs): # real signature unknown
104         """ Update a set with the union of itself and others.   更新，一般把一个list通过迭代方式更新到set集群中"""
105         pass