25、python基础学习-集合，, 1 #!/usr/

25、python基础学习-集合，, 1 #!/usr/

 1 #!/usr/bin/env python 2 #__author: hlc 3 #date: 2019/6/1 4  5 # set 集合 6 # 集合 把不同的元素组成一起形成集合，集合时python的基础类型 7 # 组成集合的成员不可重复 8 # a = [1,2,3,4,5,1,2,3,4,5,"a","a","a","b","b""b","c"] 9 # b = set(a) # 通过set关键字定义集合10 # print(a) # [1, 2, 3, 4, 5, 1, 2, 3, 4, 5, ‘a‘, ‘a‘, ‘a‘, ‘b‘, ‘bb‘, ‘c‘]11 # print(b) # {1, 2, 3, 4, 5, ‘a‘, ‘bb‘, ‘c‘, ‘b‘}12 13 # 集合对象时一个无序排列的可哈希的值：集合成员可以做字典的键14 # a = [["asdf",1244],1,2,3,4,5,1,2,3,4,5,"a","a","a","b","b""b","c"]15 # b = set(a) # TypeError: unhashable type: ‘list‘16 # print(b)17 18 # 集合分类：可变集合，不可变集合19 # 可变集合，可添加和删除元素，非可哈希，不能用作字典的键，也不能作为其他集合的元素,不可变集合与之相反20 # a = [1,2,3]21 # b = set(a) # TypeError: unhashable type: ‘set‘22 # c = {b:"sdf"}23 24 # 集合的创建25 # 由于集合没有自己的语法格式，只能通过集合的工厂方法set()和frozenset()创建26 # s1 = set("asfd")27 # s2 = frozenset("dsg")28 # print(s1,type(s1)) # {‘f‘, ‘d‘, ‘a‘, ‘s‘} <class ‘set‘>29 # print(s2,type(s2) # frozenset({‘d‘, ‘g‘, ‘s‘}) <class ‘frozenset‘>30 31 # 访问集合32 # 由于集合本身是无序的，所以不能为集合创建索引或切片操作，只能循环遍历或使用in、not in来访问或判断集合元素。33 # s1 = set("asdfsd")34 # print("a" in s1) # True35 # s1[0] # TypeError: ‘set‘ object is not subscriptable36 37 # for i in s1 :38 #     print(i)39 # d40 # s41 # a42 # f43 44 # 更新集合，可使用以下内建方法更新：45 # s1 = set("asdf")46 # s1.add()47 # s1.update()48 # s1.remove()49 # 只有可变集合才能更新50 # s1 = frozenset("gdsfg")51 # # s1.add() # AttributeError: ‘frozenset‘ object has no attribute ‘add‘52 53 # s2 = set("sdf")54 # # s2.add("mmn") # {‘f‘, ‘mmn‘, ‘d‘, ‘s‘}55 # s2.update("jkl") # {‘d‘, ‘l‘, ‘s‘, ‘k‘, ‘j‘, ‘f‘}56 # print(s2)57 58 # s1 = set(["asdf",325,"456"])59 # # s1.remove(325) # {‘456‘, ‘asdf‘}60 # s1.pop() # {‘asdf‘, 325}61 # s1.clear() # set()62 # del s1 # NameError: name ‘s1‘ is not defined63 # print(s1)64 65 # 集合类型的操作符66 # in ,not in67 # 集合等价于不等价（==，！=）68 # 子集 超集69 # print(set("asd") == set("asdasd")) # True70 # s = set("adsfas")71 # s1 = set("ads")72 # print("s" in s) # True73 # print(s > s1) # True74 75 # 联合（|） 联合（union）的操作与集合的or操作其实等价的，联合符号有个等价的方法，union（）76 # s1 = set("qewr")77 # s2 = set("ghkj")78 # s3 = s1|s279 # print(s3) # {‘e‘, ‘k‘, ‘r‘, ‘h‘, ‘w‘, ‘g‘, ‘q‘, ‘j‘}80 # print(s1.union(s2)) # {‘e‘, ‘k‘, ‘r‘, ‘h‘, ‘w‘, ‘g‘, ‘q‘, ‘j‘}81 82 a = set([1,2,3,4,5])83 b = set([4,5,6,7,8])84 85 # 交集 intersrction（）等同于 a & b86 # print(a.intersection(b)) # {4, 5}87 # 并集 union 等同于 a | b88 # print(a.union(b)) # {1, 2, 3, 4, 5, 6, 7, 8}89 # 差集 difference 等同于a - b90 # print(a.difference(b)) # {1, 2, 3}91 # print(b.difference(a)) # {8, 6, 7}92 # 对称差集（反向交集） symmetric_difference  等同于 a ^ b93 # print(a.symmetric_difference(b)) # {1, 2, 3, 6, 7, 8}94 # 父集，超集95 # print(a.issuperset(b)) # >  False96 # 子集97 # print(a.issubset(b)) # < False

25、python基础学习-集合