Overview
Python list items are accessed and changed by referring to their index number.
Changing an Item
The following will print the second item in the list.
my_list = ["Ferrari", "Maserati", "Alfa Romeo"]
my_list[1] = "Lamborghini"
print(my_list) #['Ferrari', 'Lamborghini', 'Alfa Romeo']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.
Changing a Range of Items
To change the value of items within a specific range, define a list with the new values, and refer to the range of index numbers where you want to insert the new values.
my_list = ["Lamborghini", "Ferrari", "Maserati", "Alfa Romeo"]
my_list[1:3] = ["Honda", "Toyota"]
print(my_list) #['Lamborghini', 'Honda', 'Toyota', 'Alfa Romeo']Note
The last number in a range is NOT INCLUSIVE!
Inserting More Items Than You Replace
If you insert more items than you replace, the new items will be inserted where you specified, and the remaining items will move accordingly.
my_list = ["Lamborghini", "Ferrari", "Maserati", "Alfa Romeo"]
my_list[1:2] = ["Honda", "Toyota"]
print(my_list) #['Lamborghini', 'Honda', 'Toyota', 'Maserati', 'Alfa Romeo']Inserting Fewer Items Than You Replace
If you insert fewer items than you replace, the new items will be inserted where you specified, and the remaining items will move accordingly
my_list = ["Lamborghini", "Ferrari", "Maserati", "Alfa Romeo"]
my_list[1:3] = ["Toyota"]
print(my_list) #['Lamborghini', 'Toyota', 'Alfa Romeo']Python 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), and unindexed (items cannot be referred to by index or key)
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.