Python map() Function

---

---

The Python map() function is a built-in function that allows us to transform each item from an iterable with the help of a process known as mapping. In this process, the map() function applies a function on every element of the given iterable and returns a new iterable object.

An iterable is an object that allows us to access one item at a time by iterating over them. Some examples of iterable include lists, tuples, strings, and so on.

Syntax

The syntax of the Python map() function is as follows −

map(function, iterableObject)

Parameters

The Python map() function accepts the following parameters −

• function − It represents a function which will be applied to each items of the iterables.

• iterableObject − It specifies an iterable or collection which needs to be mapped.

Return Value

The Python map() function returns a new iterator object.

map() Function Examples

Practice the following examples to understand the use of map() function in Python:

Example: Use of map() Function

The following example shows the basic usage of Python map() function. Here, we are calculating the square of each item from the specified list.

numericLst = [2, 4, 6, 8, 10]
sqrOfLst = list(map(lambda sq: sq**2, numericLst))
print("Square of the list items:")
print(sqrOfLst)

When we run above program, it produces following result −

Square of the list items:
[4, 16, 36, 64, 100]

Example: Converting Each String to Uppercase of List Using map()

In the code below, we are converting the lowercase characters of the given list of strings into uppercase. To perform this operation, we use map() function by passing the required function and list as parameter values.

stringLst = ["simply", "easy", "learning", "tutorials", "point"]
newUpprCaseLst = list(map(str.upper, stringLst))
print("The list items in uppercase:")
print(newUpprCaseLst)

Following is an output of the above code −

The list items in uppercase:
['SIMPLY', 'EASY', 'LEARNING', 'TUTORIALS', 'POINT']

Example: map() Function With Multiple Collections

The map() function can accepts multiple collection or iterables as parameter at once. In the code below, we create two lists of integers and then pass the lambda expression along with both lists to perform their addition.

listOne = [15, 14, 13]
listTwo = [41, 43, 46]
sumOfList = list(map(lambda x, y: x + y, listOne, listTwo))
print("The addition of two lists are:")
print(sumOfList)

Output of the above code is as follows −

The addition of two lists are:
[56, 57, 59]

Example: Finding Length of Each String of List Using map()

In the following code, we are using the map() function to find the length of each string from a specified list.

stringLst = ["simply", "easy", "learning", "tutorials", "point"]
lenOfLst = list(map(len, stringLst))
print("The length of each item in the List:")
print(lenOfLst)

Following is an output of the above code −

The length of each item in the List:
[6, 4, 8, 9, 5]