In Python,Lambda function is an anonymous function, which means that it is a function without a name. It can have any number of arguments but only one expression, which is evaluated and returned. It must have a return value.

Since a lambda function must have a return value for every valid input, we cannot define it withif but withoutelse as we are not specifying what will we return if theif-condition will be false i.e. itselse part.

Let's understand this with a simple example of lambda function to square a number only if it is greater than 0 usingif but withoutelse.

Example #1:

# Lambda function with if but without else.square=lambdax:x*xif(x>0)print(square(6))

Output:

File "/home/2c8c59351e1635b6b026fb3c7fc17c8f.py", line 2    square = lambda x : x*x if(x > 0)                                    ^SyntaxError: invalid syntax

The above code on execution shows SyntaxError, as we know that a lambda function must return a value and this function returns x*x if x > 0 and it does not specify what will be returned if the value of x is less than or equal to 0.

To correct it, we need to specify what will be returned if theif-condition will be false i.e. we must have to specify itselse part.

Let's see the above code with itselse part.

Code:

# Lambda function with if-elsesquare=lambdax:x*xif(x>0)elseNoneprint(square(4))

Output:

16

Example #2:The first code is withif but withoutelse then second is withif-else.

# Example of lambda function using if without elsemod=lambdax:xif(x>=0)print(mod(-1))

Output:

File "/home/20b09bdd29e24dfe24c185cd99dfcdfa.py", line 2    mod = lambda x : x if(x >= 0)                                ^SyntaxError: invalid syntax

Now, let's see it using if-else.

# Example of lambda function using if-elsemod=lambdax:xif(x>=0)else-xprint(mod(-1))

Output:

1

Example #3:The first code is with if but without else then second is with if-else.

# Example of lambda function using if without elsemax=lambdaa,b:xif(a>b)print(max(1,2))

Output:

File "/home/8cf3856fc13d0ce75edfdd76793bdde4.py", line 2    max = lambda a, b : x if(a > b)                                  ^SyntaxError: invalid syntax

Now, let's see it using if-else.

# Example of lambda function using if-elsemax=lambdaa,b:aif(a>b)elsebprint(max(1,2))print(max(10,2))

Output:

210

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