In this article, we will discuss briefly about Python Lambda function along with an example.
A Lambda function is an anonymous function which takes arguments and returns an evaluated expression. Let us see how the syntax of Python Lambda function looks like.
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Lambda Function Syntax
Before seeing examples, the following are the characteristics of a Python Lambda function which are noteworthy:
- A Lambda function can have any number of arguments but only one expression, which will be evaluated and returned.
- We are free to use lambda functions wherever function objects are required.
- return keyword is not used in Lambda function as by default lambas return a value.
Now let us create a Lambda function using Python.
Below is the lambda function to print a square of a given number:
|# python program to print a square using lambda function|
|square = lambda x : x**2|
Let us see a Lambda function accepting multiple arguments.
|# python program to find volume of a cube|
|volume = lambda l,b,h : l*b*h|
The output is 24.
Usage of Lambdas in Built-in Functions
There are some built-in functions like map(), filter(), reduce() etc. which takes a lambda as an argument.
Let us see how filter function works.
A filter() takes two parameters as arguments – a lambda function and a list. It filters the passed list and returns the values which matches the condition set by a lambda function.
Let us see an example where we want to find out the below average marks in a list.
|# python program to print below average marks|
|marks = [100, 76, 45, 28, 52, 17, 83]|
|below_average = list(filter(lambda x : x<35, marks))|