List, Ganso, dictionary in Python

First, List

A set of ordered items. Variable data type "can be added and censored"

A list is a collection of data surrounded by square brackets "[]", with different members separated by ",".

The list can include no matter what the data type, but also includes a list

The list can be visited by serial number members

Use list operations frequently:

List.append () Append member. Member data

List.pop () Delete Members, delete member I

List.count (x) count the number of occurrences in the list

List.remove () removes a member from the list. Delete Member I directly

List.extend (l) Append a list to the list L

List.reverse () Reverses the order of the members in the list

List.index (x) Get the number of references x position in the list

List.sort () sort the members in the list

List.insert () inserting data into the list insert (A, B) inserts data into the list

Available through

>>>help (list) View method details

Two, the meta-group

Immutable sequences

A tuple is a collection of data surrounded by parentheses "()", with different members separated by ","

Unlike lists: the data in a tuple cannot be changed once it is established

Interview by Subscript

Statement:

L= (a)

Tuples with 0 elements: L = ()

Tuples with 1 elements: l= (1,) note a comma

Third, the dictionary

A collection of key-value pairs (map)

A dictionary is a collection of data surrounded by curly braces "{}"

differs from list: Dictionaries are unordered, and access members by key in the dictionary.

Dictionaries are mutable and can include whatever other type

Statement:

M={K1:V1,K2:V2}

Interview M[k1] will get V1

Use dictionary operations frequently:

Dic.clear () Empty dictionary

Dic.keys () Get a list of keys

Dic.values () Get a list of values

Dic.copy () Copy Dictionary

Dic.pop (k) Delete key k

Dic.get (k) Gets the value of the key K

Dic.update () Update member, if member does not exist, equals increase

Dic.items () Gets a list of keys and values

Dic.popitem

To pass

>>>help (dict) View details

Iv. indexing and slicing of sequences

Lists, tuples, and strings are sequences

The two main features of a sequence are index operators and slice operators.

The index operator allows us to fetch a specific item from the sequence. The subscript operation, using square brackets and numbers to grab a position of the item, L[0] Grab the first element, L[-1] grab the last element

The slice operator allows us to get a slice of the sequence. That is part of the sequence.

Square brackets plus a pair of optional digits. Cut out a sub-slice L[1:3] returns 1-2 of the child slices. L[2:] From 2 to the end, l[:] the whole

List, Ganso, dictionary in Python