How to use if, else & elif in Python Lambda Functions

Lambda function can have multiple parameters but have only one expression. This one expression is evaluated and returned. Thus, We can use lambda functions as a function object. In this article, we will learn how to use if, else & elif in Lambda Functions.

Using if-else in lambda function

The lambda function will return a value for every validated input. Here, if block will be returned when the condition is true, and else block will be returned when the condition is false. 

Syntax:

lambda <arguments> : <statement1> if <condition> else <statement2>

Here, the lambda function will return statement1 when if the condition is true and return statement2 when if the condition is false.

Example:

Here, We are going to find whether a number is even or odd. when we pass number 12 to lambda function it will execute statement 1 and statement2 for 11. 

# Use if-else in Lambda Functions
# check if number is even or odd
result = lambda x : f"{x} is even" if x %2==0 else f"{x} is odd"
# print for numbers
print(result(12))
print(result(11))

12 is even
11 is odd

Using if else & elif in lambda function

We can also use nested if, if-else in lambda function. Here we will create a lambda function to check if two number is equal or greater or lesser. We will implement this using the lambda function.

Syntax:

lambda <args> : <statement1> if <condition1> else ( <statement2> if <condition2> else <statement3>)

Here, statement1 will be returned when if the condition is true, statement2 will be returned when elif true, and statement3 will be returned when else is executed. 

Example:

Here, we passed 2 numbers to the lambda function. and check the relation between them. That is if one number is greater or equal or lesser than another number

# Use if-else in Lambda Functions
# check if two numbers is equal or greater or lesser
result = lambda x,y : f"{x} is smaller than {y}" \
if x < y else (f"{x} is greater than {y}" if x > y \
               else f"{x} is equal to {y}")
# print for numbers
print(result(12, 11))
print(result(12, 12))
print(result(12, 13))

12 is greater than 11
12 is equal to 12
12 is smaller than 13