A Python lambda function is a small anonymous function without a name. It is defined using the lambda keyword and it can take any number of arguments, but it can only have one expression.

Here is an example of a simple lambda function that takes two arguments and returns their sum

add = lambda x, y: x + y

# which is same as 
def sum(x1,x2):
    return x1+x2
add = sum(x,y)

Lamda Examples

We can apply the lambda function to any argument by surrounding both the lambda function and the argument in parenthesis as shown below.

>>>  (lambda x: x + 5)(2)
7
>>> (lambda x, y = 5: x + y)(2)
7
>>>  (lambda x, y: x + y)(2, 3)
5

We can also define the lambda function first and apply it to any arguments as shown below

add = lambda x, y: x + y
add(2, 3)
# 5

Lambda functions can take other functions as arguments or return one or more functions.

# defining functions
def div(x, y):
    if(y!=0):
        return x/y
    else:
        return "Division by Zero"
def add(x, y):
    return x + y
def sub(x, y):
    return x - y

f = lambda x, y, func: func(x,y)

>>> f(2, 4, div)
0.5
>>> f(2, 4, add)
6
>>> f(2, 4, sub)
-2

Lambda functions are often used in places where you need to use a simple function for a short period of time, but you don't want to define a full function using the def keyword. They can be used, for example, as the function argument for higher-order functions like map, filter, and reduce.