Python Collection Set concepts and operations

#Collection#Concept#unordered, non-random-access, non-repeatable collection of elements#similar to the concept of a set in mathematics, it is possible to perform logical operations such as intersection, subtraction, and complement.#divided into mutable sets and non-mutable sets#Set#as a mutable collection#Increase#Delete#Change#Frozenset#Immutable Collections#after creation, cannot be deleted or modified.#definition#variable Set Set#s = {1,2,3,4}#s = set (iterable)#where iterable can be strings, lists, tuples, dictionaries, etc.#but for dict, only the element that takes the key as set#Set Deduction Formula#s = set (x**2 for x in range (1, ten) if x 2 = = 0)#s = {deduced}#Immutable Collection Frozenset#fs = Frozenset (iterable)#where iterable can be strings, lists, tuples, dictionaries, etc.#but for dict, only the element that takes the key as set#Set Deduction Formula#s = frozenset (x**2 for x in range (1, ten) if x% 2 = = 0)#Note#1. When creating an empty collection, you need to use Set () or Frozenset (), you cannot use s = {}#will be recognized as a dictionary#2. The element in the collection must be a hash value#If an object has a hash value in its own life cycle (hash value), it cannot be changed.#then it is a hash (hashable)#temporarily understood as immutable type#3. If the values of the elements in the collection are duplicated, they are combined into 1#Common Operations#Single Collection Operation#Variable Collection#Increase#S.add (Element)#Note:#the added element must be guaranteed to be a hash value#Delete#S.remove (Element)#specifies that an element in a set object be deleted#If this element is not in the collection, an error is returned#S.discard (Element)#specifies that an element in the collection be deleted#If you do not have this element, do nothing#S.pop (Element)#randomly deletes and returns an element from a collection#if the collection is empty, an error is returned#s.clear ()#empties all the elements in a collection#Change#The element is immutable type and cannot be modified#Check#Unable to query by index or key#1. Iterating through fors = {1, 2, 3} forVinchS:Print(v)#2. Access via an iteratorits = ITER (s)#Build iteratorsPrint(Next (ITS))#1Print(Next (ITS))#2Print(Next (ITS))#3 its= ITER (s)#need to start from the new, because the upper next has moved the pointer to the last#For in iterator forVinchIts :Print(v)#Immutable Collections#cannot be changed or deleted#Check#1. Iterating through for#2. Access via an iterator#Operations between Collections#intersection#intersection (iterable)#string#determines only non-numeric characters in a string#List#Meta-group#Dictionary#Value Determination key#Collection#                     ...#logic and ' & '#intersection_update (...)#Once the intersection is calculated, it is assigned to the original object again#The original object is changed#therefore, only applicable to mutable setsS1 = {1, 2, 3, 4, 5}s2= {4, 5, 6}result=s1.intersection (S2)Print(Result, type (result))#{4, 5} <class ' Set ' >result = S1 &S2Print(Result, type (result))#{4, 5} <class ' Set ' >#and set#Union ()#returns the Set#logical OR ' | '#returns the Set#Update ()#Update and set#Difference Set#difference ()#arithmetic operator minus '-'#difference_update ()#Judgment#Isdisjoint () two sets do not intersect#Issuperset () A collection contains another collection#Issubset () a collection contained in another collection#Note#variable and immutable set blending operations, returning result types to the left of the operator as the main

Python Collection Set concepts and operations