5 Clever Uses of the Walrus Operator (:=) in Python You Didn’t Know!

Master Python’s most underrated operator!

5 Clever Uses of the Walrus Operator in Python You Didn’t Know!

Walrus operator (:=) introduced in Python 3.8, also known as the assignment expression. It allows you to assign a value to a variable within an expression. This can make your code shorter, cleaner, and more efficient in certain scenarios.

Let’s explore 5 clever ways to use Walrus operator effectively! 🚀

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1. Simplifying While Loops

The walrus operator eliminates extra variable assignments in while loops.

If you don’t use Walrus operator you need a extra variable assignment :

data = input("Enter something: ") # First you have assign the variable 
while data: 
    print(f"You entered: {data}") 
    data = input("Enter something: ")

If you use Walrus operator, it eliminates the extra variable assignment before the loop and inside the loop :

while (data := input("Enter something: ")):  # It eliminates the extra variable 
    print(f"You entered: {data}")

2. Shorter List Comprehensions

You can store values inside a list comprehension using :=, avoiding redundant calculations.

If you don’t use Walrus operator you need to recalculating x**2 twice :

squares = [(x, x**2) for x in range(10) if x**2 > 20]

Walrus operator avoids recalculating x**2 twice, making the code more efficient.

squares = [(x, square) for x in range(10) if (square := x**2) > 20]

3. Optimized Regular Expressions (Regex)

When using regex, the walrus operator avoids duplicate calls to re.search().

If you don’t use Walrus operator you need for an extra variable declaration before the if statement :

import re 
 
text = "My email is test@example.com" 
match = re.search(r"[\w\.-]+@[\w\.-]+", text) 
 
if match: 
    print(f"Found email: {match.group()}")

Walrus operator eliminates the need for an extra variable declaration before the if statement :

import re 
 
text = "My email is test@example.com" 
if (match := re.search(r"[\w\.-]+@[\w\.-]+", text)): 
    print(f"Found email: {match.group()}")

4. Efficient Dictionary Updates

Instead of fetching a dictionary value multiple times, use := inside a condition.

If you don’t use Walrus operator you will going to fetch dictionary values multiple times :

inventory = {"apple": 5, "banana": 2} 
 
if "apple" in inventory and inventory["apple"] > 0: 
    inventory["apple"] -= 1 
    print(f"Apples left: {inventory['apple']}")

Walrus operator reduces fetch dictionary values multiple times that will improve the code performance :

inventory = {"apple": 5, "banana": 2} 
 
if (count := inventory.get("apple", 0)) > 0: 
    inventory["apple"] -= 1 
    print(f"Apples left: {count - 1}")

5. Condensing Function Calls in If-Statements

It Avoid redundant function calls inside if conditions.

If you don’t use Walrus operator, you will have to call the function separately.

def fetch_data(): 
    print("Fetching data...") 
    return [1, 2, 3] 
 
data = fetch_data() 
if data: 
    print(f"Received {len(data)} items")

The function only executes once, rather than calling it separately.

def fetch_data(): 
    print("Fetching data...") 
    return [1, 2, 3] 
 
if (data := fetch_data()): 
    print(f"Received {len(data)} items")

Final Thoughts

The walrus operator (:=) is a powerful tool when used wisely! It can:
- Reduce redundant calculations
- Make loops and conditions more concise
- Improve performance in list comprehensions & function calls

Have you used := in your projects? Share your thoughts in the comments!