map() Function in Python

Python’s map() is a built-in function that executes a specified function on all the elements of an iterator and returns a map object (an iterator) for retrieving the results. The elements are sent to the function as a parameter. An iterator, for example, can be a list, a tuple, a string, etc., and it returns an iterable map object.

Syntax of map function in python

The syntax for the map() function is as follows:

Syntax: map(function, iterable[, iterable1, iterable2,.., iterableN])

Parameters :

• Function: A mandatory function that will be applied to all the elements of a given iterable.
• Iterable: It is iterable and must be mapped. It could be a list, a tuple and so on. Many iterator objects may be passed to the map() function.

Return Value

The function map() applies a given function to every element of an iterable and returns an iterable map object, i.e. a tuple, a list, etc.

Python map() example

Let’s write a function to be used with map() function.

#function to square the value passed to it

def square(x): 
return x * x

It’s a simple function that returns the square of the input object.

#creating a list
my_list = [1, 2, 3, 4, 5]
result = map(square, my_list)
#prints a list containing the square values
print(result) 

The map() function takes the square function and my_list iterable. Any element in my_list is passed by map() to square function.

The function will print iterator elements with white space.

Python map() Function Example Using a Lambda Function

The first argument for map() is a function, which we use to apply to each element. For each aspect of the iterable, Python calls the function once and returns the manipulated element to a map object.

The syntax of map() with a lambda function is as follows:

map(lambda argument(s): expression)

We may implement a lambda function for a list like below with an expression we would like to use for each object in our list:

n = [5, 10, 15, 20, 25, 30]

We may use map() and lambda to use an expression against any of our numbers.

mapped = list(map(lambda x: x * x, n))

We declare elements here as x in our list. And we multiply by the same element. We move our number list as the map() iterable.

We print a listing of the map object to get the results immediately:

print(mapped)

Complete Program and output: