What are Lambda Expressions in Python?

Lambda Expression is a one-line shorthand to create a function without giving it any name.

Example

#its looks like
lambda x: x**2

# assign lambda to a variable
square_lambda=lambda x: x**2

lambda is a 'function' type.

we can invoke this as a function.

Lambda expression comes in handy when you want to create a function that you will use only one time. For example the functions we pass to the built Map (or) filter functions.

If your function could be used in many places then it should be defined like a normal function but instead, if your function is for a one-time use then use Lambda Expressions.

Lambda expressions can be used with a map function to reduce code and make it more readable.

for example, let's say we want to double every element in a list using the map function.

Without using lambda expressions:

def double_it(num):
    return num*2
my_list=[1,2,3,4,5]
new_list=map(double_it,my_list)

Using lambda expressions

my_list=[1,2,3,4,5]
(# lambda used to double each element in the list)
new_list=map(lambda x:x*2,my_list)

Lambda expressions can be used with the filter function to reduce code and make it more readable.

we will filter a list of numbers to have only odd numbers using the filter function.

Without using lambda expressions:

def is_odd(num):
    return num%2==1
my_list=[1,2,3,4,5]
new_list=filter(is_odd,my_list)

Using lambda expressions

my_list=[1,2,3,4,5]
new_list=filter(lambda num:num%2==1,my_list)