Python Lambda Function

Definition

Python have another way to create functions.

In this way, python uses lambda keyword to create a function.

Lambda function can take any number of arguments and it evaluates the expression and return the result which we can store using a variable.

Syntax

lambda arguments : expression

Example 1

x = lambda y : y * 2
print(x(5))

Output

10

Here, we have created a lambda function and give only one argument as y and the expression is y * 2.

We are storing the result to x.

We call the lambda function inside print statement by giving argument value 5 to x.

Example 2

x = lambda y,z :y * z + 2
print(x(5,10))

Output

52

Here, we created a lambda function which takes two arguments y, z, and returns the result of expression y * z + 2.

Example 3

a = lambda x,y,z : x + y * z + 2
print(a(5,10,12))

Output

127

Here, we have created a lambda function which takes three arguments and return the result after evaluation.

We are not restricted to number of arguments, we can create a lambda function which can take as much arguments as we want.

Python Function Vs Python Lambda

# multiply two numbers using lambda
a = lambda x,y: x*y
print(a(3,10))
# outputs 30

# multiply two numbers using function
def mul(x, y):
    return x*y
print(mul(3, 10))
# outputs 30

Lambda inside Functions

Power of lambda functions shown inside Python Functions as anonymous functions.

Example 1

# function argument is x
def mul(x):
    # lambda argument is y
    return lambda y: x * y
# function argument value = 5
result = mul(5)  
# lambda argument value = 4
print(result(4)) 

Output

20

Example 2

# function argument is x
def mul(x):
    # lambda argument is y
    return lambda y: x * y
myList = [10, 20, 30, 40, 50]
for i in myList:
    # function argument is i i.e. myList items
    result = mul(i)
    # lambda argument is 10
    print(result(10))

Output

100
200
300
400
500