🚀 Day 95/150 – Lambda Function Examples in Python

A lambda function is a small, anonymous function in Python. It is useful when you need a simple function for a short period without defining it using the def keyword.

The syntax of a lambda function is:

lambda arguments: expression

In this post, we'll explore four common examples of lambda functions in Python.

---

Method 1 – Simple Lambda Function

Create a lambda function to add two numbers.

add = lambda a, b: a + b

print(add(5, 3))

Output

8
Explanation

• lambda a, b: defines an anonymous function with two parameters.

• a + b is the expression whose result is returned automatically.

add(5, 3) returns 8.

---

Method 2 – Lambda with map()

Use a lambda function with map() to square each element in a list.

numbers = [1, 2, 3, 4, 5]

squares = list(map(lambda x: x ** 2, numbers))

print(squares)





Output

[1, 4, 9, 16, 25]

Explanation

• map() applies the lambda function to every element in the list.

• lambda x: x ** 2 returns the square of each number.

• list() converts the result into a list.

---

Method 3 – Lambda with filter()

Use a lambda function to filter even numbers from a list.

numbers = [1, 2, 3, 4, 5, 6]

even_numbers = list(filter(lambda x: x % 2 == 0, numbers))

print(even_numbers)






Output

[2, 4, 6]

Explanation

• filter() keeps only the elements for which the lambda function returns True.
  

• lambda x: x % 2 == 0 checks whether a number is even.

• The result is converted into a list.

---

Method 4 – Lambda with sorted()

Sort a list of tuples based on the second element.

students = [
    ("Alice", 85),
    ("Bob", 92),
    ("Charlie", 78)
]

sorted_students = sorted(students, key=lambda student: student[1])

print(sorted_students)








Output

[('Charlie', 78), ('Alice', 85), ('Bob', 92)]

Explanation

• sorted() sorts the list.

• The key parameter specifies the sorting rule.

• lambda student: student[1] tells Python to sort using the second element (marks).

---

Comparison of Methods

Method	Best For
Simple Lambda	Short mathematical operations
map()	Transforming every element
filter()	Selecting elements based on a condition
sorted()	Custom sorting

---

🔥 Key Takeaways

• A lambda function is a small anonymous function written in a single line.

• It is best suited for short and simple operations.

• map() uses lambda functions to transform data.

• filter() uses lambda functions to select matching elements.

• sorted() uses lambda functions to define custom sorting rules.

• For complex logic, use a regular function (def) instead of a lambda function.

Stay tuned for Day 96 of the #150DaysOfPython series! 🚀