Last Updated : 03 Jun, 2025
In Python, a list is a built-in dynamic sized array (automatically grows and shrinks). We can store all types of items (including another list) in a list. A list may contain mixed type of items, this is possible because a list mainly stores references at contiguous locations and actual items maybe stored at different locations.
Example :
Python
# Creating a Python list with different data types
a = [10, 20, "GfG", 40, True]
print(a)
# Accessing elements using indexing
print(a[0]) # 10
print(a[1]) # 20
print(a[2]) # "GfG"
print(a[3]) # 40
print(a[4]) # True
# Checking types of elements
print(type(a[2])) # str
print(type(a[4])) # bool
Explanation:
Creating a ListNote: Lists Store References, Not Values
Each element in a list is not stored directly inside the list structure. Instead, the list stores references (pointers) to the actual objects in memory. Example (from the image representation).
- The list a itself is a container with references (addresses) to the actual values.
- Python internally creates separate objects for 10, 20, "GfG", 40 and True, then stores their memory addresses inside a.
- This means that modifying an element doesn’t affect other elements but can affect the referenced object if it is mutable
Here are some common methods to create a list:
Using Square Brackets Python
# List of integers
a = [1, 2, 3, 4, 5]
# List of strings
b = ['apple', 'banana', 'cherry']
# Mixed data types
c = [1, 'hello', 3.14, True]
print(a)
print(b)
print(c)
[1, 2, 3, 4, 5] ['apple', 'banana', 'cherry'] [1, 'hello', 3.14, True]Using list() Constructor
We can also create a list by passing an iterable (like a string, tuple or another list) to list() function.
Python
# From a tuple
a = list((1, 2, 3, 'apple', 4.5))
print(a)
[1, 2, 3, 'apple', 4.5]Creating List with Repeated Elements
We can create a list with repeated elements using the multiplication operator.
Python
# Create a list [2, 2, 2, 2, 2]
a = [2] * 5
# Create a list [0, 0, 0, 0, 0, 0, 0]
b = [0] * 7
print(a)
print(b)
[2, 2, 2, 2, 2] [0, 0, 0, 0, 0, 0, 0]Accessing List Elements
Elements in a list can be accessed using indexing. Python indexes start at 0, so a[0] will access the first element, while negative indexing allows us to access elements from the end of the list. Like index -1 represents the last elements of list.
Python
a = [10, 20, 30, 40, 50]
# Access first element
print(a[0])
# Access last element
print(a[-1])
Adding Elements into List
We can add elements to a list using the following methods:
# Initialize an empty list
a = []
# Adding 10 to end of list
a.append(10)
print("After append(10):", a)
# Inserting 5 at index 0
a.insert(0, 5)
print("After insert(0, 5):", a)
# Adding multiple elements [15, 20, 25] at the end
a.extend([15, 20, 25])
print("After extend([15, 20, 25]):", a)
After append(10): [10] After insert(0, 5): [5, 10] After extend([15, 20, 25]): [5, 10, 15, 20, 25]Updating Elements into List
We can change the value of an element by accessing it using its index.
Python
a = [10, 20, 30, 40, 50]
# Change the second element
a[1] = 25
print(a)
[10, 25, 30, 40, 50]Removing Elements from List
We can remove elements from a list using:
a = [10, 20, 30, 40, 50]
# Removes the first occurrence of 30
a.remove(30)
print("After remove(30):", a)
# Removes the element at index 1 (20)
popped_val = a.pop(1)
print("Popped element:", popped_val)
print("After pop(1):", a)
# Deletes the first element (10)
del a[0]
print("After del a[0]:", a)
After remove(30): [10, 20, 40, 50] Popped element: 20 After pop(1): [10, 40, 50] After del a[0]: [40, 50]Iterating Over Lists
We can iterate the Lists easily by using a for loop or other iteration methods. Iterating over lists is useful when we want to do some operation on each item or access specific items based on certain conditions. Let's take an example to iterate over the list using for loop.
Using for Loop Python
a = ['apple', 'banana', 'cherry']
# Iterating over the list
for item in a:
print(item)
apple banana cherry
Nested Lists in PythonTo learn various other methods, please refer to iterating over lists.
A nested list is a list within another list, which is useful for representing matrices or tables. We can access nested elements by chaining indexes.
Python
matrix = [
[1, 2, 3],
[4, 5, 6],
[7, 8, 9]
]
# Access element at row 2, column 3
print(matrix[1][2])
Quiz: Python List Operation ProgramsTo learn more, please refer to Multi-dimensional lists in Python
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