Python-collection and python collection

Python-collection and python collection

Collection

The main function is to compare the information in the list and test the link.

Features:
1. remove duplicates. If a list is converted into a collection, deduplication is automatically performed.
2. Test the relationship between the two groups of data, such as intersection, difference set, and Union set.
3. No insert function. You can add only.
4. A disordered, non-repeated data combination

5. No insert function. You can only add one.

Appears in the form of {}, type: set

List_1 = [, 33, 1] # create list_1 = set (list_1) # convert the keyword to print (list_1, type (list_1) # output set, and perform de-duplication directly. {1, 2, 3, 4, 5, 33} <class 'set'> # in braces. The data type is set.

Intersection:

List_1 = set ([1, 2, 3, 5, 3, 4, 2, 33, 1]) list_2 = set ([2, 2, 4, 5, 6, 7, 8]) print (list_1.intersection (list_2) # intersection, the duplicate items in the two sets are displayed. {2, 4, 5}

Abbreviation of intersection:

List_1 = set ([1, 2, 3, 5, 3, 4, 2, 33, 1]) list_2 = set ([2, 2, 4, 5, 6, 7, 8]) print (list_1 & list_2) # abbreviation of intersection {2, 4, 5}

Union:

List_1 = set ([, 1]) list_2 = set ([,]) print (list_1.union (list_2) # union, that is, remove and merge the duplicate options in the two lists. {1, 2, 3, 4, 5, 33, 6, 7, 8}

Abbreviation of union.

List_1 = set ([1, 2, 3, 5, 3, 4, 2, 33, 1]) list_2 = set ([2, 2, 4, 5, 6, 7, 8]) print (list_1 | list_2) # Union abbreviations: {1, 2, 3, 4, 5, 33, 6, 7, 8}

The difference set is the data in 1 but not in 2.

List_1 = set ([1, 2, 3, 5, 3, 4, 2, 33, 1]) list_2 = set ([2, 2, 4, 5, 6, 7, 8]) print (list_1.difference (list_2 )) # difference set {1, 3, 33}

Abbreviation of difference set:

List_1 = set ([1, 2, 3, 5, 3, 4, 2, 33, 1]) list_2 = set ([2, 2, 4, 5, 6, 7, 8]) print (list_1-list_2) # difference set abbreviations: {1, 3, 33}

A subset is used to determine whether List 1 contains all the data in list 3.

List_1 = set ([1, 2, 3, 5, 3, 3, 2, 33, 1]) list_3 = set ([1, 2, 3]) print (list_3.issubset (list_1 )) # subset True # Return false or True

The parent set is used to determine whether all content in list 3 is included in List 1.

List_1 = set ([1, 2, 3, 5, 3, 3, 2, 33, 1]) list_3 = set ([1, 2, 3]) print (list_1.issuperset (list_3 )) # True for parent set # false or True

The symmetric difference set removes the numbers in both lists and merges them together.

List_1 = set ([, 1]) list_2 = set ([,]) print (list_1.1_ric_difference (list_2 )) # print (list_1 ^ list_2) # abbreviation of Symmetric Difference set {33, 4, 5, 88}

The intersection is used to determine whether the two lists have the same information.

List_1 = set ([, 1]) list_2 = set ([,]) print (list_1.isdisjoint (list_2 )) false # if there is an intersection, False is displayed. If not, True is displayed.

Add:

List_1 = set ([999, 444,333,222, 33, 1]) list_1.add () # Add print (list_1) list_1.update ([]) # add multiple print (list_1) {1, 2, 3, 4, 5, 33,999} {1, 2, 3, 4, 5, 33,999,333,444,222}

Delete:

List_1 = set ([2,333, 333, 1]) list_1.remove () # Delete print (list_1)

Delete one randomly:

List_1 = set ([1, 2, 3, 5, 4,333]) print (list_1.pop () 1 # Return the deleted Value

Delete. If it is not in the Set, no error is returned.

List_1 = set ([4,333, 222,]) list_1.discard () # No or error in the set.

Show the length after deduplication:

list_1 = set([1,2,3,5,4,333])print(len(list_1))6

Determines whether the number is in the collection.

List_1 = set ([4,333,]) print (6 in list_1) False # If not, False is displayed. If yes, True is displayed.

Calculate whether the number is not in this set.

List_1 = set ([4,333,]) print (6 not in list_1) True # True is displayed if not present, False is displayed if

Copy:

List_1 = set ([1, 2, 3, 5, 4,333]) list_2 = list_1.copy () # copy to list_2. Print (list_2) print (type (list_2) {1, 2, 3, 4, 5,333} <class 'set'>