What is Lambda Function in Python: Simple Explanation and Examples

A lambda function in Python is a small, anonymous function defined with the lambda keyword. It can take any number of arguments but has only one expression, which is returned automatically.

How It Works

Think of a lambda function as a quick, one-line recipe that you write on a sticky note instead of a full cookbook recipe. It lets you create a simple function without giving it a name. This is useful when you need a small function just once or in a short place.

Normally, functions have a name and a block of code. But a lambda function is like a mini-function that fits in one line and returns the result of its single expression automatically. You give it inputs, and it quickly gives you the output.

Example

This example shows a lambda function that adds two numbers. It takes two inputs and returns their sum.

python

add = lambda x, y: x + y
result = add(3, 5)
print(result)

Output

8

When to Use

Use lambda functions when you need a simple function for a short time, especially as an argument to other functions like map, filter, or sorted. They help keep your code short and clean without defining a full function.

For example, if you want to sort a list of names by their length, a lambda function can quickly tell the sorting function how to compare them.

Key Points

• Anonymous: No need to name the function.
• Single expression: Only one line of code that returns a value.
• Useful for short tasks: Ideal for quick, simple functions.
• Common in functional programming: Works well with functions like map, filter, and sorted.

Key Takeaways

A lambda function is a small, unnamed function defined with the lambda keyword.

It can take any number of inputs but only one expression that is returned automatically.

Use lambda functions for simple, short tasks to keep code concise and readable.

They are often used as arguments to functions like map, filter, and sorted.