Python - Add List Items

Add List Items

Adding list items in Python implies inserting new elements into an existing list. Lists are mutable, meaning they can be modified after creation, allowing for the addition, removal, or modification of their elements.

Adding items in a list typically refers to appending new elements to the end of the list, inserting them at specific positions within the list, or extending the list with elements from another iterable object.

We can add list items in Python using various methods such as append(), extend() and insert(). Let us explore through all these methods in this tutorial.

Adding List Items Using append() Method

The append() method in Python is used to add a single element to the end of a list.

We can add list items using the append() method by specifying the element we want to add within the parentheses, like my_list.append(new_item), which adds new_item to the end of my_list.

Example

In the following example, we are adding an element “e” to the end of the list “list1” using the append() method −

list1 = ["a", "b", "c", "d"]
print ("Original list: ", list1)
list1.append('e')
print ("List after appending: ", list1)

Output

Following is the output of the above code −

Original list: ['a', 'b', 'c', 'd']
List after appending: ['a', 'b', 'c', 'd', 'e']

Adding List Items Using insert() Method

The insert() method in Python is used to add an element at a specified index (position) within a list, shifting existing elements to accommodate the new one.

We can add list items using the insert() method by specifying the index position where we want to insert the new item and the item itself within the parentheses, like my_list.insert(index, new_item).

Example

In this example, we have an original list containing various items. We use the insert() method to add new elements to the list at specific positions −

list1 = ["Rohan", "Physics", 21, 69.75]

list1.insert(2, 'Chemistry')
print ("List after appending: ", list1)

list1.insert(-1, 'Pass')
print ("List after appending: ", list1)

After appending ‘Chemistry’ to the list, we get the following output −

List after appending: ['Rohan', 'Physics', 'Chemistry', 21, 69.75]

Then, by inserting ‘Pass’ at the index “-1”, which originally referred to 69.75, we get −

List after appending: ['Rohan', 'Physics', 'Chemistry', 21, 'Pass', 69.75]

We can see that “Pass” is not inserted at the updated index “-1”, but the previous index “-1”. This behavior is because when appending or inserting items into a list, Python does not dynamically update negative index positions.

Adding List Items Using extend() Method

The extend() method in Python is used to add multiple elements from an iterable (such as another list) to the end of a list.

We can add list items using the extend() method by passing another iterable containing the elements we want to add, like my_list.extend(iterable), which appends each element from the iterable to the end of my_list.

Example

In the below example, we are using the extend() method to add the elements from “another_list” to the end of “list1” −

# Original list
list1 = [1, 2, 3]
# Another list to extend with
another_list = [4, 5, 6]

list1.extend(another_list)
print("Extended list:", list1)

Output

Output of the above code is as follows −

Extended list: [1, 2, 3, 4, 5, 6]