Collection of Python Basics

#gather
#Set definition method Braces {} and set
se={1,2,3}
#The collection is unordered, and there cannot be repeated elements, and it is variable.
#The collection is unordered, so each return order is returned randomly, and the collection has no index

#Set the most important uses, and cross
#& The intersection returns the same elements of the two sets, if there are no identical elements, it returns the empty value of the empty value set()
#| Union removes duplicates from two sets and forms a new set
#- The difference set is to remove the common part of the two sets and form a new set. For example, the a set - the b set displays the result that the a set removes the duplicates of the b set, and any elements in the b set will not appear in the new set. in the collection.
# If you don't understand the difference set, see the example below
se={1,2,3}
s2={'a',1,2,3}
s2-se
'''
{'a'}
'''
se-s2
'''
set()
'''


#Common methods of collection
# pop randomly removes an element in the set, because the set is unordered, so pop cannot pass in coordinates. Deletion is random
# remove specifies to delete an element se.remove(2) deletes 2 in the se set
# update can add multiple values ​​at once
# add adds one value at a time
# QQ:8131432