Python List

Before introducing Python List, let us review

Python Variable

Python List: Variables

As in the case in math, Python uses variables to name unknown quantities

Python List: Variables

​In Python, the unknown quantities are called Data Types

Notice how the data type 'girl' and 'boy' are represented

Python: Variable vs List

Notice that each Variable is linked to one unknown?

That is y = 2, y = 'boy' or y = 'books'​

In Python, lists are similar but, are used to store multiple items in a single variable.

​Notice:

• List conveniently assign multiple items to a variable.

• List is identified using [ ]

• each item is separated using commas.

Python: List

You can view listings as chess with drawers.

• Each item will be placed in one drawer.

• Each drawer will be numbered, starting from 0. (this Python is called indexing.

​0

​1

​2

​3

​4

Python: List

Example: The following is an example of a list...

​y = [2, 'boy', 'book']

​ 2 in slot 0

​y =

​ boy in slot 1

​ book in slot 2

More About List

List items are...

• ordered,

• changeable, and

• allow duplicate values.

More About List

List items are ordered,

• This means that the items have a defined order, and that order will not change.

• If you add new items to a list, the new items will be placed at the end of the list.

More About List

List items are ordered,

• This means that each item occupies a specific position (having defined order), and that the order will not change.

• If you add new items to a list, the new items will be placed at the end of the list.

More About List

List items are changeable,

• This means that the items can be change by adding, and removing items after it has been created.

More About List

List items allow for duplicate values.

This means that lists can have items with the same value

thislist = ["apple", "banana", "cherry", "apple", "cherry"]

​This is possible since each item in the list will occupy its own position (slot).