set
Similarly dict, is a set of key not stored value
Nature: a collection of unordered and non-repeating elements
格式：集合名={元素1，元素2……，元素n}
create
Create a set must have a list or tuple as output set
Repeating element is automatically filtered in the set
s1 = set([1,2,3,4,4，5，5，5])
print(s1) #输出{1，2，3，4，5}
s2 = set((1,2,3,4,5))
s3 = set({1:"good",2:"nice"})#只将字典中的key保存为set的元素
print(s2)
print(s3) #只输出字典中的key
add (elementary data type / tuples)
Personal understanding: If the elements set itself can not change
s4 = set([1,2,3,4,5])
s4.add(6) #可以添加重复的，但是没有效果
print(s4)
s4.add([9,8,7])#报错，因为set的元素不能是列表，因为列表可变
s4.add((9,8,7)) #不会报错，但是将元组作为元素
s4.add([1:"good",2:"nice"]) #报错，因为字典的元素可变，所以不能作为set的元素
update()
Insert the whole list, tuple, string, inserting break
s5 = set([1,2,3,4,5])
s5.update([6,7,8,9])
print(s5)
s5.update("sunck")
print(s5)
s5.update({1:"good",22:"nice"})
print(s5)
remove(elem)
Remove elements, if the elem does not exist, an error
s6 = set([1,2,3,4,5])
s6.remove(5)
pop()
Random delete elements, if there is no element in the collection, but also pop, it will error
格式：集合名.pop()
discard()
格式：集合名.discard(elem)
If the element is present, delete, and if not, no operation
s = {1,2,3,4}
s.discard(3)
Traversal
Cyclic
s7 = set([1,2,3,4,5])
for i in s7:
print(i)
for index,data in enumerate(s7):
print(index,data)
ps: So far, dict and set can be used enumerate () method
Intersection
s8 = set([1,2,3,4,5])
s9 = set([8,9])
a1 = s8 & s9
print(type(a1)) #set的交集还是set
print(a1)
Union
s2 = s8 | s9
ps: set with less than the actual, mostly type conversion
tuple --> set
set --> list
set --> tuple
Quite conversion and mandatory
mainly used to re-set
myList = [1,1,1,12,2,2,3,4,5,6]
print(list(set(myList)))