Lists are fundamental data structure in Python that allows for storing and manipulating a collection of objects. The Python List append() method is used for appending and adding elements to the end of the Python List.
Syntax of List append()
The syntax of the Python List append() method is as follows:
Syntax: list.append(item)
Parameters:
- item: an item (number, string, list etc.) to be added at the end of the list, The parameter is mandatory and omitting it can give an error.
Returns: N/A (The method doesn’t return any value)
How To Add Elements to a List in Python
The list is a sequence datatype used to store elements. Lists are mutable i.e., we can add/remove elements. There are many different methods to add elements to a list in Python.
Here are some ways by which you can add elements to a List are given below.
- Using the Append() Method
- Adding List to the List
- Using the Concatenation operator
- Using List Slicing
Adding elements to the end of a list with Python’s append() method increases the list’s size. It offers a practical method to add one or more elements to a list that already exists. Here is an example of using the List Append() method.
Example 1: Adding Element to the List Using Append() Method
In this example, we will append a single element at the end of the given list using the List append() method in Python.
Python3
# my_listmy_list = ['Lazyroar', 'for'] # Add 'Lazyroar' to the listmy_list.append('Lazyroar') print(my_list) |
Output:
['Lazyroar', 'for', 'Lazyroar']
Time complexity: O(1)
Space complexity: O(1)
Example 2: Adding List to the List
In this example, we will append a complete list at the end of the given list.
Python3
# my_listmy_list = ['Lazyroar', 'for', 'Lazyroar'] # another listanother_list = [6, 0, 4, 1] # append another_list to my_listmy_list.append(another_list) print(my_list) |
Output:
['Lazyroar', 'for', 'Lazyroar', [6, 0, 4, 1]]
Note: A list is an object. If you append another list onto a list, the parameter list will be a single object at the end of the list. If you want to append the elements of a list to another list you can use Python’s List extend() method.
Time complexity: O(1) or constant time. This is because lists can be accessed randomly using indexing, so the last element can be accessed easily in O(1) time.
Example 3: Adding Element in List Using Concatenation Operator
Another way to add elements to a list is using the concatenation operator( ‘+’ ), in this we create a new list by combining the existing list with another list that contains the new element.
Python3
# Existing listmy_list = [9, 5, 7] new_element = 3my_list = my_list + [new_element]print(my_list) |
Output:
[9, 5, 7, 3]
Time complexity: O(1)
Space complexity: O(1)
Example 4: Adding Element to a List Using List Slicing
Another way to add elements to a list is using list slicing, this allows you to modify a portion of a list by assigning new values to it. To add elements to specific positions within a list, we can use list slicing with the insert() method.
Python3
# Existing listmy_list = [3, 4, 6] # Insert element 5 at index 2my_list.insert(2, 5) print(my_list) |
Output:
[3, 4, 5, 6]
Time complexity: O(1)
Space complexity: O(1)
Note: If you need to add items of a list (rather than the list itself) to another list, use the extend() method.
