A list is a mutable sequence of elements surrounded by square brackets. If you’re familiar with JavaScript, a Python list is like a JavaScript array. It’s one of the built-in data structures in Python. The others are tuple, dictionary, and set.
A list can contain any data type such as an integer, float, string, and boolean:
num_list = [1, 2, 3, 10]
float_list = [2.9, 3.9, 4.6]
boo_list = [True, False]
string_list = ['JavaScript', 'Python', 'freeCodeCamp']
It can also contain a mixture of those data types:
mixed_list = ['freeCodeCamp', 1, 1.1, True]
Since lists are mutable, you can add items to them or remove items from them. This article will show you how to add to a list.
What We’ll Cover
How to Add to a List in Python
Python provides 3 methods with which you can add to a list. Those methods are append()
, extend()
, and insert()
.
How to Add to a List with the append()
Method
The append()
element adds to the end of a list.
Provided we have the following list:
sports_list = ["Football", "Basketball", "Baseball", "Tennis"]
If I want to add “Cricket” to the end of that list, I can do it with the append()
method this way:
sports_list.append("Cricket")
Printing sports_list
to the console results in this:
['Football', 'Basketball', 'Baseball', 'Tennis', 'Cricket']
You can see Cricket
was added to the last index in the list.
You can also prompt the user to add to the list this way:
sports_list = ["Football", "Basketball", "Baseball", "Tennis"]
new_sport = input("Please add a new sport: ")
sports_list.append(new_sport)
print(sports_list)
How to Add to a List with the insert()
Method
The append()
method helps you add to the end of a list, but if you want to add to any index you want, you can use the insert()
method.
To use the insert()
method for adding to a list, you need to specify the index, then the item you want to add:
insert(index, item)
I have added Athletics
to the first index (0) of the sports_list
this way:
sports_list = ["Football", "Basketball", "Baseball", "Tennis"]
sports_list.insert(0, "Athletics")
print(sports_list)
# Output: ['Athletics', 'Football', 'Basketball', 'Baseball', 'Tennis']
I also added Wrestling
to index 2 (the 3rd index) this way:
sports_list.insert(2, "Wrestling")
print(sports_list)
# Output: ['Athletics', 'Football', 'Wrestling', 'Basketball', 'Baseball', 'Tennis']
How to Add to a List with the extend()
Method
The extend()
method adds an iterable data item to a list or adds one list to another list. So, with it, you can add a tuple, set, or dictionary to a list.
sports_list = ["Football", "Basketball", "Baseball", "Tennis"]
# add another list
sports_list.extend(["Golf", "Boxing"])
# Append a tuple
sports_list.extend(("Netball", "TT"))
print(sports_list)
# Output: ['Football', 'Basketball', 'Baseball', 'Tennis', 'Golf', 'Boxing', 'Netball', ‘TT']
How to Add a Dictionary to a List with the append()
Method
If you try to add a dictionary to a list with the extend()
method, you only get the keys and not the values:
sports_list = ["Football", "Basketball", "Baseball", "Tennis"]
sports_dict = {1: "Netball", 2: "Chess"}
sports_list.extend(sports_dict)
print(sports_list)
# Output: ['Football', 'Basketball', 'Baseball', 'Tennis', 1, 2]
You can loop through the dictionary and then use the append method to add it to the list. This will give you the dictionary’s keys and values as a set of tuples in the list:
sports_list = ["Football", "Basketball", "Baseball", "Tennis"]
sports_dict = {1: "Netball", 2: "Chess"}
for k, v in sports_dict.items():
sports_list.append((k, v))
print(sports_list)
# Output: ['Football', 'Basketball', 'Baseball', 'Tennis', (1, 'Netball'), (2, 'Chess')]
If you want the dictionary as it is right inside the list, you can just use the append method without a loop:
sports_list = ["Football", "Basketball", "Baseball", "Tennis"]
sports_dict = {1: "Netball", 2: "Chess"}
sports_list.append(sports_dict)
print(sports_list)
# Output: ['Football', 'Basketball', 'Baseball', 'Tennis', {1: 'Netball', 2: 'Chess'}]
Conclusion
In this article, we looked at how to use the append()
, insert()
, and extend()
methods to add to a list in Python.
What you add to a list does not have to be a single element. That’s why I showed you how to use the extend()
method to help you add iterables like lists, tuples, and dictionaries to a list.
Thank you for reading.