Python - Add List Items

Python lists are dynamic, which means we can add items to them anytime. In this guide, we'll look at some common ways to add single or multiple items to a list using built-in methods and operators with simple examples:

Add a Single Item Using append()

append() method adds one item to the end of the list. It modifies the original list in-place.

li = [1, 2, 3]
li.append(4)
print(li)

[1, 2, 3, 4]

Explanation: append() method is used to add the number 4 to the list li. After running the code, the list becomes [1, 2, 3, 4].

Add Multiple Items Using extend()

extend() method adds each element from an iterable (like a list or tuple) to the end of the existing list.

li = [1, 2, 3]
li.extend([4, 5, 6])
print(li)

[1, 2, 3, 4, 5, 6]

Explanation: extend() method adds all items from the iterable (like a list) to the end of the original list. The result will be [1, 2, 3, 4, 5, 6].

Adding Items at Specific Position Using insert()

insert(index, item) method places the item at the specified position. Existing elements are shifted to the right. We can also use insert() to add multiple items at once.

li = [1, 2, 3]
li.insert(1, 10)
print(li)
li = [1, 2, 3]
for i in [4, 5, 6]:
    li.insert(1, i)  # Inserts items at index 1 one by one
print(li)

[1, 10, 2, 3]
[1, 6, 5, 4, 2, 3]

Explanation:

• insert(1, 10) adds 10 at the second position (index 1) of the list. After running the code, the list becomes [1, 10, 2, 3].
• In second part, we insert items from the list [4, 5, 6] into the original list li. The items are added at index 1 but because we are inserting one by one, the list is modified each time.

Combine Lists Using the + Operator

The + operator joins two or more lists and returns a new list without modifying the original ones.

a = [1, 2, 3]
b = [4, 5, 6]
c = a + b
print(c)

[1, 2, 3, 4, 5, 6]

Explanation: The + operator combines the two lists a and b into a new list c. The result is [1, 2, 3, 4, 5, 6] and the original lists remain unchanged.

Adding Items in a Loop

We can use a loop (like for) to add items conditionally or repeatedly using append().

li = []
for i in range(5):
    li.append(i)
print(li)

[0, 1, 2, 3, 4]

Explanation: This loop appends values from 0 to 4 to the list li. After running the loop, the list li will contain [0, 1, 2, 3, 4].

Also read: append(), extend(), insert()