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This article will explain in detail what set and frozenset are in Python collection types. The editor thinks it is very practical, so I share it with you as a reference. I hope you can get something after reading this article.

Collection type-set, frozenset

A set object is an unordered set of hashable objects that are unique. Common uses include member detection, removal of duplicates from sequences, and set class computation in mathematics, such as intersection, union, difference and symmetric difference, etc.

The constructors of the two classes work in the same way:

Class set ([iterable])

Class frozenset ([iterable])

Collections can be created in several ways:

Use the comma separation of elements within curly braces: {'jack',' sjoerd'}

Use set derivation: {c for c in 'abracadabra' if c not in' abc'}

Use the type constructor: set (), set ('foobar'), set ([' a', 'baked,' foo'])

Examples of set and frozenset provide the following operations: len (s)

Calculate the number of s elements in the collection

X in s

Detect whether x is a member of s

X not in s

Detect whether x is not a member of s

Isdisjoint (other)

It is used to determine whether two sets contain the same element. If no True is returned, False is returned.

X = {"apple", "banana", "cherry"} y = {"google", "runoob", "facebook"} z = x.isdisjoint (y) print (z) issubset (other)

Used to determine whether all elements of the collection are included in the specified collection. If so, return True, otherwise return False

X = {"a", "b", "c"} y = {"f", "e", "d", "c", "b", "a"} z = x.issubset (y) issuperset (other)

Used to determine whether all elements of the specified collection are included in the original collection, returning True if so, False otherwise.

X = {"f", "e", "d", "c", "b", "a"} y = {"a", "b", "c"} z = x.issuperset (y) print (z) union (* others)

Returns the union of two sets, that is, the elements that contain all sets, and duplicate elements appear only once

X = {"apple", "banana", "cherry"} y = {"google", "runoob", "apple"} z = x.union (y) print (z) intersection (* others)

Used to return elements contained in two or more collections, that is, intersections.

X = {"apple", "banana", "cherry"} y = {"google", "runoob", "apple"} z = x.intersection (y) print (z) difference (* others)

The subtraction used to return the collection, that is, the returned collection elements are contained in the first collection, but not in the second collection (the parameters of the method).

X = {"apple", "banana", "cherry"} y = {"google", "microsoft", "apple"} z = x.difference (y) print (z) symmetric_difference (other)

Returns a collection of elements that do not repeat in two collections, that is, the elements that exist in both collections are removed.

X = {"apple", "banana", "cherry"} y = {"google", "runoob", "apple"} z = x.symmetric_difference (y) print (z) copy ()

Used to copy a collection.

Sites = {"Google", "Runoob", "Taobao"} x = sites.copy () print (x) can be used for set but not for immutable frozenset instance operations: update (* others)

Used to modify the current collection, you can add a new element or collection to the current collection. If the added element already exists in the collection, the element will appear only once, and duplicate elements will be ignored.

X = {"apple", "banana", "cherry"} y = {"google", "runoob", "apple"} x.update (y) print (x) intersection_update (* others)

The intersection_update () method is used to get elements that overlap in two or more collections, that is, computed intersections.

The intersection_update () method is different from the intersection () method because the intersection () method returns a new collection, while the intersection_update () method removes non-overlapping elements from the original collection.

X = {"apple", "banana", "cherry"} # y collection does not contain banana and cherry, is removed y = {"google", "runoob", "apple"} x.intersection_update (y) print (x) difference_update (* others)

The difference_update () method is used to remove elements that exist in both collections.

The difference between the difference_update () method and the difference () method is that the difference () method returns a new collection that removes the same element, while the difference_update () method removes the element directly from the original collection without returning a value.

X = {"apple", "banana", "cherry"} y = {"google", "microsoft", "apple"} x.difference_update (y) print (x) symmetric_difference_update (other)

The symmetric_difference_update () method removes elements in the current collection that are the same in another specified collection and inserts different elements in another specified collection into the current collection.

X = {"apple", "banana", "cherry"} y = {"google", "runoob", "apple"} x.symmetric_difference_update (y) print (x) add (elem)

Used to add elements to the collection, and if the added element already exists in the collection, no action is performed.

Fruits = {"apple", "banana", "cherry"} fruits.add ("orange") print (fruits) remove (elem)

Used to remove the specified element from the collection.

Fruits = {"apple", "banana", "cherry"} fruits.remove ("banana") print (fruits) discard (elem)

Remove the element elem if it exists in the collection

Fruits = {"apple", "banana", "cherry"} fruits.discard ("banana") print (fruits) pop ()

Removes and returns any element from the collection. A KeyError is thrown if the collection is empty.

Fruits = {"apple", "banana", "cherry"} fruits.pop () print (fruits) clear ()

Used to remove all elements from the collection.

Fruits = {"apple", "banana", "cherry"} fruits.clear () print (fruits) Relational Operation sq1024 = {"Page", "Old Boy", "Haifeng", "Ma JJ", "Old Village head", "Black Girl", "Alex"} s_pornhub = {"Alex", "Egon", "Rain", "Horse JJ", "Nick", "Jack"} print (swarm 1024 & s_pornhub) # intersection Elements in both setprint (slots 1024 | s_pornhub) # Union or sets print (slots 1024-s_pornhub) # difference, only in 1024print (s_pornhub-slots 1024) # subtractions, only in pornhubprint (slots 1024 ^ s_pornhub) # symmetrical differences, people who walk two boats out on what are set and frozenset in Python collection types, that ends here. Hope that the above content can be helpful to you, so that you can learn more knowledge, if you think the article is good, please share it for more people to see.

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