[Python] use of set set

set Created collection ​ It's a set of elements that don't repeat in disorder , Relationship testing is possible , Delete duplicate data , You can also compute the intersection 、 Difference set 、 And set etc. .​

Set operator

Operation Python Operator meaning Example intersection & Take two sets of common elements (intersection)>>> set1 & set2
{3} Combine | Take two sets of all elements (union)>>> set1 | set2
{1,2,3,4,5} Difference set - Take elements that one set does not have in another set (difference)>>> set1 - set2
{1,2}
>>> set2 - set1
{4,5} Symmetric difference set ^ Take set A and B It doesn't belong to A&B The elements of (symmetric_difference)>>> set1 ^ set2
{1,2,4,5}

Add elements to the collection ：

a = {"1", "2", "3"}
a.add("qwq")
print(a)

 

Like adding elements from a list to a collection ：

a = {"1", "2", "3"}
a.update(["qwq","QAQ"])
print(a)

But if update If a single string is written in it, it will be split

a = {"1", "2", "3"}
a.update("QAQ")
print(a)

 

Get the elements unique to each of the two collections ：

a = {"1", "2", "3"}
b = {"1", "4"}
ret = a.symmetric_difference(b)

Delete elements from the collection  

a = {"1", "2", "3"}
a.remove("1")
print(a)