Lambda Function in Python

Lambda functions are throw-away functions, i.e., they are just needed; they have been created and can be used anywhere a function is required.

Lambda functions are so-called because they are not declared as other functions using the keyword def. They are created using the lambda keyword.

The syntax of the lambda function is given below:

lambda arguments: expression

The arguments contain a comma-separated list of arguments, and the expression is an arithmetic expression that uses these arguments. The function can be assigned to a variable to give it a name.

Lambda function contains the following features:

• Lambda function has no name.
• Lambda functions can take any number of arguments.
• Lambda function definition does not have an explicit return statement, but it always contains an expression that is returned.
• They cannot access variables other than those in their parameter list.
• Lambda function cannot even access global variables.
• We can pass lambda functions as arguments in other functions.
• We can pass lambda arguments to a function.
• We can define a lambda that receives no arguments but simply returns an expression.

Example A:

sum=lambda x, y:x+y
print("Sum=",sum(10,20))

Output:

Sum= 30

Example B:

def min(a,b):
    if(a<b):
        return(a)
    else:
        return(b)
sum=lambda x,y:x+y # lambda function to add two numbers
sub=lambda x,y:x-y # lambda function to subtract two numbers
print("smaller of two numbers=",min(sum(-6,-8),sub(-1,2))) # pass lambda functions as arguments

Output:

smaller of two numbers= -14

Example C:

def f1(f,n):
    print(f(n))
twice=lambda x:x*2
thrice=lambda x:x*3
f1(twice,4)
f1(thrice,3)

Output:

8

9

Example D:

x=lambda:sum(range(1,10))
print(x())

Output

45