list1=[1,2,3,4]
list2=[3,4,5,6]
list3=[]
for i in list1:
  if i in list2:
    list3.append(i)
print(list3)

my_list = [1, 2, 3, 4, 2, 3, 1, 2, 2]
# 转化为集合
my_set = set(my_list)
print(list(my_set))

> my_set = set(('apple',))
> my_set
{'apple'}

# add 作为一个整体添加到集合中
my_set = set()
my_set.add("abc")
print(my_set)  
#update 是把要传入的元素拆分，做为个体传入到集合中
my_set = set()
my_set.update("abc")
print(my_set)

#remove 如果集合种有，则直接删除；如果没有，程序报错 格式：集合名.remove(元素)
my_set = {11, 13, 15} 
my_set.remove(13)
print(my_set) my_set.remove(131)
print(my_set)  
#pop 随机删除集合中的元素 如果集合中没有元素则程序报错
my_set = {11, 13, 15}
my_set.pop()
print(my_set)  
#discard 如果集合中元素存在，直接删除； 如果元素不存在 不做任何操作  格式: 集合名.discard(元素)
my_set = {11, 13, 15} 
my_set.discard(13)
print(my_set) 
my_set.discard(131)
print(my_set)

set1 = {9, 2, 3, 4}
set2 = {3, 4, 5, 16}
new_set = set1 & set2
print(new_set)
# result {3, 4}

set1 = {1, 2, 3, 4}
set2 = {3, 5, 5, 6}
new_set = set1 | set2
print(new_set)
# result {1, 2, 3, 4, 5, 6}

set1 = {1, 2, 3, 4}
set2 = {3, 4, 5, 6}
new_set = set1 - set2
print(new_set)
# result {1, 2}

set1 = {1, 2, 3, 4}
set2 = {3, 4, 5, 6}
new_set = set1 ^ set2
print(new_set)
# result {1,2,5,6}

set1 = { 3, 4}
set2 = {3, 4, 5, 6}
# 判断set1是否是set2的子集
print(set1.issubset(set2))
# result True

set1 = { 3, 4}
set2 = {3, 4, 5, 6}
# 判断set1是否是set2的父集
print(set1.issuperset(set2))
# result False

s={34,56,76,34,56,54,43,23,56}
for i in s:
  print(i) ##迭代输出其内容
for i,v in enumerate(s):
  print('index: %s,value: %s' %(i,v))
"""
result:
index: 0,value: 34
index: 1,value: 43
index: 2,value: 76
index: 3,value: 54
index: 4,value: 23
index: 5,value: 56
"""