Overview
Python lists are used to store multiple items in a single variable. List items are indexed, the first item has index [0], the second item has index [1], the third item has index [2], etc.
Note
Arrays count starting from zero NOT one. So item 1 is position [0], item 2 is position [1], and item 3 is position [2] … and so on.
Creating a List
Lists are created using square brackets. List items are ordered as created, but that can be changed at a later point.
Duplicate values in the same list are allowed. Lists can be of any data type and can be a mixture of data types.
my_list1 = ["Ferrari", "Maserati", "Alfa Romeo", "Maserati"]
my_list2 = [2, 4, 6, 9]
my_list3 = [True, True, False]
my_list4 = ["Maserati", True, 2, 4, False, "Ferrari"]Another way to create a list is to use the list() constructor.
my_list = list(("Ferrari", "Maserati", "Alfa Romeo"))Note
If you add new items to an existing list, the new items will be placed at the end of the list.
Getting the Number of Items in a List
To determine how many items are in a list, the len() function is used.
my_list = ["Ferrari", "Maserati", "Alfa Romeo"]
print(len(my_list))3Python Notes:
- The most recent major version of Python is Python 3; however, Python 2 is still in use and quite popular, although not being updated with anything other than security updates
- Python uses new lines to complete a command, as opposed to other programming languages which often use semicolons or parentheses
- Python relies on indentation, using whitespace to define scope, such as the scope of loops, functions, and classes; other programming languages often use curly-brackets for this purpose
- Python string methods return new values, and DO NOT change the original string
- Python tuples are unchangeable after created (their items CANNOT be changed or re-ordered at a later point)
- Python sets are unordered (may appear in random orders when called), unchangeable (the value of individual items cannot be changed after creation), unindexed (items cannot be referred to by index or key), and duplicates are NOT ALLOWED
- As of v3.7, Python dictionaries are ordered and duplicates ARE ALLOWED; in v3.6 and earlier, dictionaries were unordered (did not have a defined order and could not be referred to using an index)
We’d like to acknowledge that we learned a great deal of our coding from W3Schools and TutorialsPoint, borrowing heavily from their teaching process and excellent code examples. We highly recommend both sites to deepen your experience, and further your coding journey. We’re just hitting the basics here at 1SMARTchicken.