Lists
Coding: Introduction to Python v3, topic 2.1.1
Lists
Lists are a data structure quite similar to an array.
Lists
- Lists store multiple elements of different data types under the same identifier.
- There can be a variable number of elements - they never get full.
Lists in pseudocode
- A list can be declared as follows:
- pupils = []
- Values can be added to the end of the list as follows:
- pupils.append("Alice")
- Values can be accessed as follows:
- print("The first student is " + pupils[0])
2D Lists
A 2D list is the data structure which consists of a list of lists.
2D List
- A 2D list is a data structure where lists are filled with other lists.
- This can be used to represent a 2D surface, or records.
Accessing elements
- To access an individual list we can access the list as usual:
- list = my2DList[4]
- To access an individual element, we use this syntax:
- list[5][0]
- This would get the first element ([0]), of the sixth list ([5]).
Uses of 2D lists
- 2D lists are often used to represent a 2D surface, for example, a chess board:
- Each element of the 2D list could contain the chess piece in that location.
- 2D lists can be used to represent a database:
- Each inner list represents a single record (row) in the database.
- The outer list contains all the records, representing the entire table.
Test yourself on Lists
Which of these are true of lists?
How is a list created?
What would the command list[5].append(3) do to a 2D list?