Python: 6 Ways to Iterate Through a List (with Examples)

Using a for loop

Using a for loop is the most common approach to iterating through a list in Python. You can access each element individually and perform operations on them as needed.

Example:

# Creating a list
my_list = ["dog", "cat", "rabbit", "parrot", "turtle"]

# Iterating over the list using a for loop
for item in my_list:
    # print each item in uppercase
    print(item.upper())

Output:

DOG
CAT
RABBIT
PARROT
TURTLE

Using the enumerate() function

The Python built-in enumerate() function provides a way to iterate over a list while also tracking the index of each element.

Example:

# Creating a list
fiction_creatures = ["ghost", "goblin", "ghoul", "zombie", "devil", "vampire"]

# Iterating over the list using enumerate()
for index, item in enumerate(fiction_creatures):
      # Print index and value of each element
    print(f"Index: {index}, Value: {item}")

Output:

Index: 0, Value: ghost
Index: 1, Value: goblin
Index: 2, Value: ghoul
Index: 3, Value: zombie
Index: 4, Value: devil
Index: 5, Value: vampire

Using a for loop and the range() function

Besides the enumerate() function mentioned in the previous section, you can use this technique to access both list elements and their indices:

1. Use the range() function to generate indices corresponding to the list length (returned by the len() function).
2. Use a for loop to iterate over the range of indices.
3. Access each element using its index within the loop.

Example:

# Creating a list
my_list = ['Python', 'JavaScript', 'FastAPI', 'Sling Academy']

# Get the length of the list
length = len(my_list)

# Iterating over the list using a for loop and range()
for i in range(length):
    item = my_list[i]  # Accessing each element using its index
    print(item)  # Print each element

Output:

Python
JavaScript
FastAPI
Sling Academy

Using a while loop

A while loop can be used to iterate over a list by incrementing a counter until reaching the list length. It provides flexibility in controlling the loop flow but requires a little additional code.

Example:

# Creating a list
games = ["Elden Ring", "CS:GO", "Dota 2", "League of Legends", "Valorant", "Diablo 4"]

# Iterating over the list using a while loop
counter = 0
while counter < len(games):
    item = games[counter]  # Accessing each element using the counter
    print(item)  # Print each element
    counter += 1  # Increment the counter

Output:

Elden Ring
CS:GO
Dota 2
League of Legends
Valorant
Diablo 4

Using list comprehension

List comprehension is a syntactic construct that allows you to create a new list based on an existing list or another iterable object, using a concise and expressive syntax. Python is one of the few programming languages that support this beautiful syntax (Haskell, C#, Ruby).

Example:

origial_list = ['one', 'two', 'three', 'four', 'five']

# create a new list with uppercase items
new_list = [item.upper() for item in origial_list]
print(new_list)

Output:

['ONE', 'TWO', 'THREE', 'FOUR', 'FIVE']

Using a high-order function

High-order functions like map() and filter() can be used to iterate over a list while applying transformations or filtering based on a condition.

Example of using the map() function:

# Creating a list of numbers
numbers = [1, 2, 3, 4, 5]

# Using map() to square each number
squared_numbers = list(map(lambda x: x**2, numbers))
print(squared_numbers)

Output:

[1, 4, 9, 16, 25]

Example of using the filter() function:

# Creating a list of numbers
numbers = [1, 2, 3, 4, 5]

# Using filter() to select even numbers
even_numbers = list(filter(lambda x: x % 2 == 0, numbers))
print(even_numbers)

Output:

[2, 4]