Category: python
Introduction to Lambda Functions
Published on 24 Jul 2026
Explanation
A lambda function is an anonymous (unnamed) function in Python that is defined using the lambda keyword. Lambda functions are
Code:
# Lambda function to add two numbers add = lambda a, b: a + b print(add(10, 20)) # Lambda function to find square square = lambda x: x * x print(square(5)) # Lambda function to find maximum maximum = lambda a, b: a if a > b else b print(maximum(25, 40))
Explanation
The map() function applies a given function to every element in an iterable such as a list or tuple and
Code:
numbers = [1, 2, 3, 4, 5] # Square each number squares = list(map(lambda x: x * x, numbers)) print(squares) # Convert strings to integers values = ['10', '20', '30'] integers = list(map(int, values)) print(integers) # Convert names to uppercase names = ['john', 'alice', 'david'] upper_names = list(map(str.upper, names)) print(upper_names)
Explanation
The filter() function is used to select elements from an iterable that satisfy a specified condition. It takes two arguments:
Code:
numbers = [10, 15, 20, 25, 30, 35, 40] # Filter even numbers even_numbers = list(filter(lambda x: x % 2 == 0, numbers)) print(even_numbers) # Filter numbers greater than 20 greater_than_20 = list(filter(lambda x: x > 20, numbers)) print(greater_than_20) names = ['John', '', 'Alice', '', 'David'] valid_names = list(filter(lambda name: name != '', names)) print(valid_names)
Explanation
The reduce() function repeatedly applies a function to the elements of an iterable until a single value is produced. It
Code:
from functools import reduce
numbers = [10, 20, 30, 40, 50]
# Sum of numbers
total = reduce(lambda a, b: a + b, numbers)
print('Total:', total)
# Product of numbers
product = reduce(lambda a, b: a * b, numbers)
print('Product:', product)
# Maximum number
maximum = reduce(lambda a, b: a if a > b else b, numbers)
print('Maximum:', maximum)
Explanation
Lambda functions, map(), filter(), and reduce() are often used together to process collections efficiently. A common workflow is to filter
Code:
from functools import reduce
prices = [1000, 2500, 5000, 7500, 900]
# Select products costing at least 2000
filtered_prices = list(filter(lambda price: price >= 2000, prices))
print('Filtered:', filtered_prices)
# Apply 10% discount
discounted_prices = list(map(lambda price: price * 0.9, filtered_prices))
print('Discounted:', discounted_prices)
# Calculate final bill
final_amount = reduce(lambda a, b: a + b, discounted_prices)
print('Final Amount:', final_amount)