2.1.1

Lists

Test yourself on Lists

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Lists

Lists are a data structure quite similar to an array.

Lists

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

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

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

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

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 can store a record of the database.
    • The outer list can store each record.
Jump to other topics
1

Introduction to Python

1.1

Python

1.1.1Python
1.2

Input & Output

1.2.1Input & Output
1.3

Data Types

1.3.1Data Types
1.4

Variables & Constants

1.4.1Variables & Constants
1.5

Operators

1.5.1Arithmetic & Relational Operators1.5.2Boolean & Assignment Operators 2
1.6

Program Flow

1.6.1Selection1.6.2Iteration
2

Data Structures

2.1

Lists & Strings

2.1.1Lists2.1.2Strings
2.2

File Handling

2.2.1File Handling
3

Modularity

3.1

Subroutines

3.1.1Subroutines
3.2

Data Flow

3.2.1Data Flow
4

Good Practice

4.1

Naming & Whitespace

4.1.1Identifiers4.1.2Whitespace
4.2

Comments

4.2.1Comments
4.3

Exceptions

4.3.1Exceptions

Practice questions on Lists

Can you answer these? Test yourself with free interactive practice on Seneca — used by over 10 million students.

  1. 1
    Which of these are true of lists?True / false
  2. 2
    How is a list created?Multiple choice
  3. 3
    The main difference between a list and an array is that:Multiple choice
  4. 4
    What would the command list[5].append(3) do to a 2D list?Multiple choice
Answer all questions on Lists

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Iteration

Strings