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基本数据类型-集合(set)_上周内容回顾(列表_元组_集合)
上周内容回顾
字符串
数字
列表
元组
字典
可变不可变:
1、可变:列表,字典
2、不可变: 字符串,数字,元组
访问顺序:
1、直接访问:数字
2、顺序访问:字符串,列表,元组
3、映射: 字典
存放元素个数:
容器类型:列表,元组,字典
原子:数字,字符串
set集合是一个无序而且不重复的集合,有些类似于数学中的集合,也可以求交集,求并集等
集合特性:
1、不同元素组成
2、无序
3、集合中元素必须是不可变类型
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
set用法练习
1 s1={1,2,3,1} #定义一个set s1 如果s1={}为空则默认定义一个字典 2 s2=set([2,5,6]) #定义一个set s2 3 print(s1) #s1={1,2,3} 自动去除重复的元素 4 5 s1.add(5) #s1={1,2,3,5} 添加一个元素 6 print(s1) 7 8 s3=s1.difference(s2) #返回一个s1中存在而不存在于s2的字典s3,s3={1,3},而s1并没有改变 9 print(s3) 10 11 s1.difference_update(s2) #s1跟新成上面的s3 s1={1,3} 12 s1.discard(1) #删除元素1,不存在的话不报错 s1={3} 13 print(s1) 14 s1.remove(3) #删除元素3,不存在的话报错 s1={} 15 print(s1) 16 s1.update([11,2,3]) #跟新s1中的元素,其实是添加 s1={11,2,3} 17 print(s1) 18 k=s1.pop() #删除一个元素,并将删除的元素返回给一个变量,无序的,所以并不知道删除谁 19 20 21 s1={1,2,3,4} #这里重新定义了集合s1,s2 22 s2={3,4,5,6} 23 r1=s1.intersection(s2) #取交集,并将结果返回给一个新的集合 r1={3,4} 24 print(r1) 25 print(s1) 26 s1.intersection_update(s2) #取交集,并将s1更新为取交集后的结果 s1={3,4} 27 print(s1) 28 29 k1=s1.issubset(s2) #s1是否是s2的的子序列是的话返回True,否则False 这里k1=true 30 print(k1) 31 k2=s1.issuperset(s2) #s1是否是s2的父序列 k2=False 32 33 k3=s2.isdisjoint(s1) #s1,s2,是否有交集,有的话返回False,没有的话返回True 34 print(k3) 35 s1.update([1,2]) #s1={1,2,3,4} 36 r3=s1.union(s2) #取并集将结果返回给r3 r3={1,2,3,4,5,6} 37 print(r3) 38 r2=s1.symmetric_difference(s2) #r2=s1并s2-s1交s2 r2={1,2,5,6} 39 print(r2) 40 s1.symmetric_difference_update(s2) #s1更新为 s1并s2 - s1交s2 s1={1,2,5,6} 41 print(s1)
基本数据类型-集合(set)_上周内容回顾(列表_元组_集合)
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