python整理-Day3

set

无须，不重复,可嵌套的集合

  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. 清除内容"""
 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.
 39
 40         If the element is not a member, do nothing. 移除指定元素，不存在不保错
 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，否则返回False"""
 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.
 71         Raises KeyError if the set is empty. 移除元素
 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.
 78
 79         If the element is not a member, raise a KeyError. 移除指定元素，不存在保错
 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
 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 """
105         pass 

练习：

#!/usr/bin/env python# -*- coding: utf-8 -*-# Author:wzc

dic1={    "a":"8",    "b":"4",    "d":"2",}

dic2={    "a":"4",    "b":"4",    "c":"2",}

old_dic=set(dic1)print(old_dic)new_dic=set(dic2)print(new_dic)add_key=old_dic.difference(new_dic)print(add_key)del_key=new_dic.difference(old_dic)print(del_key)up_key=list(old_dic.intersection(new_dic))print(up_key)for i in list(up_key):    #print(dic1[i],dic2[i])    if dic1[i] != dic2[i]:        print(i)

展示结果：

{‘a‘, ‘d‘, ‘b‘}
{‘a‘, ‘c‘, ‘b‘}
{‘d‘}
{‘c‘}
[‘a‘, ‘b‘]
a

函数

定义和使用

函数的定义主要有如下要点：

• def：表示函数的关键字
• 函数名：函数的名称，日后根据函数名调用函数
• 函数体：函数中进行一系列的逻辑计算，如：发送邮件、计算出 [11,22,38,888,2]中的最大数等...
• 参数：为函数体提供数据
• 返回值：当函数执行完毕后，可以给调用者返回数据。