Change List Items in Python

A list is a mutable data type in Python. This means that its contents can be modified in place after the object is stored in memory. You can assign a new value at a given index position in the list.

Syntax

list1[i] = new_value

Changing a Single List Item

You can change the value of a specific item in a list by assigning a new value to its index.

Example

list3 = [1, 2, 3, 4, 5]
print("Original list", list3)

list3[2] = 10
print("List after changing value at index 2:", list3)

Output:

Original list [1, 2, 3, 4, 5]
List after changing value at index 2: [1, 2, 10, 4, 5]

Changing Consecutive List Items

You can replace multiple consecutive items in a list with another sublist.

Example

list1 = ["a", "b", "c", "d"]
print("Original list:", list1)

list2 = ['Y', 'Z']
list1[1:3] = list2

print("List after changing with sublist:", list1)

Output:

Original list: ['a', 'b', 'c', 'd']
List after changing with sublist: ['a', 'Y', 'Z', 'd']

Changing a Range of List Items

If the replacement sublist has more items than the slice being replaced, the extra items will be inserted.

Example (More Items)

list1 = ["a", "b", "c", "d"]
print("Original list:", list1)

list2 = ['X', 'Y', 'Z']
list1[1:3] = list2

print("List after changing with sublist:", list1)

Output:

Original list: ['a', 'b', 'c', 'd']
List after changing with sublist: ['a', 'X', 'Y', 'Z', 'd']

Example (Fewer Items)

If the sublist used for replacement has fewer items than the slice being replaced, the extra items in the original list will be removed.

list1 = ["a", "b", "c", "d"]
print("Original list:", list1)

list2 = ['Z']
list1[1:3] = list2

print("List after changing with sublist:", list1)

Output:

Original list: ['a', 'b', 'c', 'd']
List after changing with sublist: ['a', 'Z', 'd']