What is lambda in Python? Why is it used?

A lambda function is an anonymous function in Python.

syntax → lambda <argument name> : <return expression>

It starts with the keyword, followed by a comma-separated list of zero or more arguments, followed by the colon and the return expression.

For example, lambda x, y, z: x+y+z would calculate the sum of the three-argument values x+y+z.

Use of Lambda Functions

  • uses lambda functions once we require a nameless function for a brief period of your time.
  • Lambda functions reduce the number of lines of code when compared to normal python functions.
  • They are generally used when a function is needed temporarily for a short period of time
  • Using the lambda function, you can define a function and call it immediately at the end of the definition. This can’t be done with def functions.
  • In Python, we generally use Lambda Functions as an argument to a higher-order function (a function that takes in other functions as arguments).

For Example, These are used together with built-in functions like filter(), map(), and reduce()


sequences = [10,2,8,7,5,4,11]
squared_result = map (lambda x: x*x, sequences)

Output → [100, 4, 64, 49, 25, 16, 121]


  • Internally, both lambda and def functions work exactly the same
  • Lambda functions can have 0 or 1 expression, not more.

No expression

x = lambda : "hello world"

output → hello world

Single expression

new_single = lambda x : (x%2)

output → 0

  • Lambda functions accept all kinds of arguments, just like a normal def function.
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