Python map() Function

In this Python guide, we are going through the Python map() function to execute a specific function for each item for an iterable. map function in Python is the most important function when you want to execute a function for each item of an iterable.

In the previous Python built-in functions tutorials, we have seen various functions along with examples.

What is the Python map() function?

The Python map() function is a built-in function. map() function in Python is used to apply a specific function on each item of an iterable ( list, tuple, string, etc) and return a map object and at the end, the map object can convert into a list using the list() function.

Syntax

The syntax of the map() function in python is:-

map(function, iterable)

Parameter

map function in Python accepts two parameters.

• function:- Required, the function executed for each item.
• iterable:- Required. A sequence, collection, or an iterator object.

Python map() function examples

Let’s understand the Python map() function along with various examples so that you can get more clarity with that.

Example: Converting each integer item of the list into a string

lst = [2, 4, 6, 8, 10, 12]
result = map(str, lst)
print("List after converting item to string:- ", list(result))

Output

List after converting item to string:-  ['2', '4', '6', '8', '10', '12']

Example: Converting each item of the tuple to their Unicode character

Convert a tuple of integers into a set of strings using the map function.

x = ("A", "b", "C", "d", "E")
y = map(ord, x)
print(list(y))

Output

[65, 98, 67, 100, 69]

map() function with a custom function

Python map() function is also responsible for accepting custom functions which are not come with Python by default.

Example: Square each item of the list using the map() function

In this example, we will pass a list having some integer value to the map() function and map() function apply a function to each item of the list and calculate the square of a particular item and finally return a list.

def calculate_square(n):
    """
    :param n: n refers to each item of the list
    :return: return square n * n
    """
    return n * n


lst = [2, 4, 6, 8, 10, 12]
result = map(calculate_square, lst)
print("Map Object:- ", result)
print("Square of list items", list(result))

Output

Map Object:-  <map object at 0x000002BE2D57ACE0>
Square of list items [4, 16, 36, 64, 100, 144]

Example: Calculating the length of string items of the list

Calculate the length of each string item of the tuple using the map() function.

def calculate_length(n):
    """
    :param n: n refers to the each item of the list
    :return: length of n
    """
    return len(n)


lst = ("Java", "Python", "C++", "Dot Net")
result = map(calculate_length, lst)
print("Map Object:- ", result)
print("Square of list items", list(result))

Output

Map Object:-  <map object at 0x000001F4E54FAC50>
Square of list items [4, 6, 3, 7]

Example: Using map() function with a lambda function

In this example, I am trying to add 10 to each item of the tuple. Here I am using the Python lambda function. You can explore more about the Python lambda function.

lst = [2, 4, 6, 8, 10, 12]
result = map(lambda x: x + 10, lst)
print("New List:- ", list(result))

Output

New List:-  [12, 14, 16, 18, 20, 22]

Example: Passing more than one iterables to the map()

In this example, I am passing two iterable ( lst1 and lst2 ) to the function map () function, and the map() function uses an addition function which is responsible for adding the sum of the corresponding items of the iterable

def addition(x, y):
    """
    
    :param x: x refer to item of the first iterable
    :param y: y refer to item of the second iterable
    :return: return sum of x and y
    """
    return x + y

# first iterable
lst1 = [12, 14, 16, 18]
# second iterable
lst2 = [20, 40, 50, 60]

result = map(addition, lst1, lst2)
print("Result:- ", list(result))

Output

Result:-  [32, 54, 66, 78]

Conclusion

In this tutorial, you have learned all about the Python map function to execute a specific function for each item of an iterable.
This is the best built-in function when you want to perform a specific operation on each item of iterable.

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