集合：一个无序的，不重复的数据组合
- 去重，列表变集合，自动去重
- 关系测试，测试两组数据之间的交集，差集，并集等关系
去重
set0 = set("hello") # 创建字符集合 print("set0:", set0) # ->set0: {'e', 'l', 'h', 'o'} list1 = [1, 2, 3, 1, 2] set1 = set(list1) # 创建数值集合 print(type(set1), set1) # -><class 'set'> {1, 2, 3} set2 = {1, 2, 4, 0} set3 = {1, 2} print("set1:", set1) # ->set1: {1, 2, 3} print("set2:", set2) # ->set2: {0, 1, 2, 4} print("set3:", set3) # ->set3: {1, 2}
关系测试
# 交集 print("set1 ∩ set2:", set1.intersection(set2)) # ->set1 ∩ set2: {1, 2} print("set1 & et2:", set1 & set2) # ->set1 & et2: {1, 2} # 并集 print("set1 ∪ set2:", set1.union(set2)) # ->set1 ∪ set2: {0, 1, 2, 3, 4} print("set1 | set2:", set1 | set2) # ->set1 | set2: {0, 1, 2, 3, 4} # 差集 in set1 but no in set2 print("set1-set2:", set1.difference(set2)) # ->set1-set2: {3} print("set2-set1:", set2.difference(set1)) # ->set2-set1: {0, 4} print("set1-set2:", set1 - set2) # ->set1-set2: {3} print("set2-set1:", set2 - set1) # ->set2-set1: {0, 4} # 对称差集 二者中不相交的部分 print("set1-set2 ∪ set2-set1:", set1.symmetric_difference(set2)) # ->set1-set2 ∪ set2-set1: {0, 3, 4} print("set1 ^ set2:", set1 ^ set2) # ->set1 ^ set2: {0, 3, 4} # 子集 print("set3∈set1?:",set3.issubset(set1)) # ->set3∈set1?: True print("set3 <= set1:",set3.issubset(set1)) # ->set3 <= set1: True # 父集 print("set3∈set1?:",set1.issuperset(set3)) # ->set3∈set1?: True print("set1 >= set3:",set1.issuperset(set3)) # ->set1 >= set3: True # 相等 print("set1 == set2", set1 == set2) #->set1 == set2 False print("set1 != set2", set1 != set2) #->set1 != set2 True # 不相交 set4 = {5, 6, 7} print(set4) # ->{5, 6, 7} print("set1∩set2==null?", set1.isdisjoint(set2)) # ->set1∩set2==null? False print("set1∩set4==null?", set1.isdisjoint(set4)) # ->set1∩set4==null? True
基本操作
# 添加 print(set1) # ->{1, 2, 3} set1.add(5) # 添加一项 print(set1) # ->{1, 2, 3, 5} set1.update([6, 7, 8, 8]) #添加多项 print(set1) # ->{1, 2, 3, 5, 6, 7, 8} # 删除 set1.remove(5) # 指定删除,不存在会报错 print(set1) # ->{1, 2, 3, 6, 7, 8} set1.pop() # 随意删除 print(set1) # ->{2, 3, 6, 7, 8} set1.discard(888) # 指定删除，不存在不会报错 # 长度 print(len(set1)) # ->5 # 成员检查,字符串，列表，集合，字典 print(6 in set1) # ->True print(9 not in set1) # ->True
