python集合的相关操作

集合

langs = {"python","cpp","java","go"}

print(langs)

print(type(langs))

'''

输出结果：

{'python', 'java', 'cpp', 'go'}

<class 'set'>

'''

#给集合去重

list1 = [1,1,2,3,4,5,6,6]

set1 = set(list1) #把集合转换成列表

print(set1) #输出{1, 2, 3, 4, 5, 6}

list1 = list(set1) #把列表转换成集合

#判断元素是否在集合中

A = {1,2,3}

i = 1 in A

print(i) #输出True

x = 4 not in A

print(x) #True

#追加元素

A.add(5)

#删除元素

A.remove(3) #若被删元素不存在则会报异常

A.discard(99) #若被删元素不存在不会报异常

print(A.pop()) #随机弹出一个元素

#集合的拷贝

C = A.copy()

#提取公有元素---交集

A = {"a","b","b","c","d"}

B = {"b","d","e","f","g"}

AB1 = A.intersection(B)

print(AB1) #输出{'d', 'b'}

AB2 = A & B

print(AB2) #输出{'d', 'b'}

#并集

A = {1,2,3,4,5,5,5}

B = {"a","b","c","d","e","e","e"}

print(A | B) #{1, 2, 3, 4, 5, 'c', 'b', 'd', 'e', 'a'}

print(A.union(B)) #{1, 2, 3, 4, 5, 'c', 'b', 'd', 'e', 'a'}

#差集

A = {"a","b","b","c","d"}

B = {"b","d","e","f","g"}

AB1 = A.difference(B) #取出A中有B中没有的东西{'a', 'c'}

AB2 = B.difference(A) #取出B中有A中没有的东西{'e', 'g', 'f'}

print(AB2)

AB3 = A - B #{'a', 'c'}

AB4 = B - A #{'e', 'g', 'f'}

print(AB3)

#对称差集

AB5 = A.symmetric_difference(B)

print(AB5) #保留集合中各自独有的元素{'c', 'f', 'a', 'g', 'e'}

#对比两个集合是否相等

A = {"a","b","b","c","d"}

B = {"b","d","e","f","g"}

AB = A == B

print(AB) #输出False

#两集合去重，会直接修改集合中的元素

A = {"a","b","b","c","d"}

B = {"b","d","e","f","g"}

B.difference_update(A) #将b中a的元素删除

print(B) #{'f', 'e', 'g'}

#交集更新

A = {"a","b","b","c","d"}

B = {"b","d","e","f","g"}

A.intersection_update(B) #在集合A中保留AB中共有的元素

print(A) #{'d', 'b'}

#删除集合

B.clear()

print(B) #输出set()

#集合的计算

A = {"a","b","b","c","d"}

B = {"b","d","e","f","g"}

x = max(A)

y = min(A)

z = sum(A)