python 基础 set 集合类型补充

为啥今天又重提这个数据类型呢？平时用的少，等要用起来的时候才发现，自己对这块啥都不知道了，so，今天就把这块再梳理一下咯。

一、set集合，是一个无序且不重复的元素集合。这一点是非常重要的。

二、集合中的方法介绍：

 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，添加元素

         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. 清除内容"""
         pass

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

     def difference(self, *args, **kwargs): # real signature unknown
         """
         Return the difference of two or more sets as a new set. A中存在，B中不存在

         (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.  从当前集合中删除和B中相同的元素"""
         pass

     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. 移除指定元素，不存在不保错
         """
         pass

     def intersection(self, *args, **kwargs): # real signature unknown
         """
         Return the intersection of two sets as a new set. 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.  取交集并更更新到A中 """
         pass

     def isdisjoint(self, *args, **kwargs): # real signature unknown
         """ Return True if two sets have a null intersection.  如果没有交集，返回True，否则返回False"""
         pass

     def issubset(self, *args, **kwargs): # real signature unknown
         """ Report whether another set contains this set.  是否是子序列"""
         pass

     def issuperset(self, *args, **kwargs): # real signature unknown
         """ Report whether this set contains another set. 是否是父序列"""
         pass

     def pop(self, *args, **kwargs): # real signature unknown
         """
         Remove and return an arbitrary set element.
         Raises KeyError if the set is empty. 移除元素
         """
         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. 移除指定元素，不存在保错
         """
         pass

     def symmetric_difference(self, *args, **kwargs): # real signature unknown
         """
         Return the symmetric difference of two sets as a new set.  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. 对称差集，并更新到a中 """
         pass

     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

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

集合方法摘录

三、常用方法举例：

 linux = set(['alex','jack','rain','sb'])
 python = set(['sb','alex','mack','rachel'])

 #集合linux与集合python 中都有的（交集）
 a = linux.intersection(python)
 print(a) # {'sb', 'alex'}

 # 求差集 linux 中有而python中没有的
 b = linux.difference(python)
 print(b) # {'rain', 'jack'}

集合部分的简单操作也就这些内容了。