Python Anonymous OR Lambda Function Example

In this post, we would love to share everything about anonymous function in python with you. Like what is an anonymous function in python, how to write syntax of anonymous function in python, how to create an anonymous function in python and how to use this function in python with examples?

What is Lambda/Anonymous Function in Python

In Python programming language, anonymous function is a function that is also known as a lambda function. defined without a name. Functions that are defined without a name and without def keyword are also called anonymous function or lambda function.

You may have found in the previous tutorial how to create a function in Python and how to use this function. If you have not read this tutorial on how to create a function and how to use it, you can click here.

In Python programming, whenever we create a normal function, we define it by using the def keyword only.

Syntax of Lambda Function in python

A lambda/anonymous function in python has the following syntax.

lambda arguments: expression

Example of Lambda Function in python

Let’s take a simple example of the Lambda Function in python. So that you will understand how to make it and how to use it:

# Python Program to display the uses of lambda functions

myFunc = lambda x: x * 2

# Output: 10
print(myFunc(5))

In the above lambda function program, lambda x: x * 2 is the simple lambda function. Here x is the argument of lambda function in python and x * 2 is the expression of lambda function program.

This function has no name. It returns a function object which is assigned to the identifier myFunc. We can now call it as a normal function.

The statement

myFunc = lambda x: x * 2

It is almost the same as the function below:

def myFunc(x):
   return x * 2

Use of Lambda Function in python

Whenever a function is created for a short time and that too without defining its name. At that time we do the lambda function.

Let us now use the Lambda function with some Python in-built functions ( filter(), map() ) and take the example:

Example: python lambda function with filter

First of all, you should know that the Python filter function takes some arguments.

Now we will create a program using filter () and lambda function, in this function we will pass a list and this function will give us a list of even numbers from given list by using filter and lambda function.

# python lambda function list filter

a = [1, 5, 4, 6, 8, 11, 3, 12]

b = list(filter(lambda x: (x%2 == 0) , a))

print(b)

Output

[4, 6, 8, 12]

Example: python anonymous/lambda function map

First of all, you should know that the Python map function takes some arguments.

Now we will create a program using map () and lambda function, in this function we will pass a list and this function will double the number of the given list using map and lambda function.

# python lambda function list map

a = [2, 4, 6, 8, 10, 12]

b = list(map(lambda x: x * 2 , a))

print(b)

Output

[4, 8, 12, 16, 20, 24]

Example: python lambda function with reduce

First of all, you should know that the Python reduce function takes some arguments.

Now we will create a program using reduce() and lambda function, in this function, we will pass a list and this function will sum of the given number list using reduce() and lambda function.

# python lambda function list filter

a = [1, 5, 4, 6, 8, 11, 12]

sum = reduce((lambda x, y: x + y), a) 

print(sum

Output

47