In this tutorial, I will explain how to use the Python map function in Python. In one of my projects with the USA clients, I encountered this scenario while working with large datasets and performing repetitive tasks. Let us see how the various map() methods in Python work, with examples.
map() Function in Python
The map function in Python takes two arguments: a function and an iterable. It applies the specified function to each item of the iterable and returns a map object (an iterator) of the results. The general syntax is:
map(function, iterable)Read How to Use the randint() Function in Python?
Examples
Let us see some examples to understand more about the topic.
Example 1: Convert Temperatures from Celsius to Fahrenheit
Suppose you have a list of temperatures in Celsius and you want to convert them to Fahrenheit. Here’s how you can do it using the map function:
celsius_temperatures = [0, 20, 30, 40, 100]
def celsius_to_fahrenheit(celsius):
return (celsius * 9/5) + 32
fahrenheit_temperatures = list(map(celsius_to_fahrenheit, celsius_temperatures))
print(fahrenheit_temperatures)Output:
[32.0, 68.0, 86.0, 104.0, 212.0]I have executed the above example code and added the screenshot below.
Check out How to Use wait() Function in Python?
Example 2: Capitalize Names
Imagine you have a Python list of names and you want to capitalize each name. Using the map function, you can achieve this effortlessly:
names = ["john", "jane", "michael", "susan"]
capitalized_names = list(map(str.capitalize, names))
print(capitalized_names)Output:
['John', 'Jane', 'Michael', 'Susan']I have executed the above example code and added the screenshot below.
Example 3: Calculate Square Roots
If you have a list of numbers and you want to calculate the square root of each number, you can use the map function with the math.sqrt function:
import math
numbers = [4, 16, 25, 36, 49]
square_roots = list(map(math.sqrt, numbers))
print(square_roots)Output:
[2.0, 4.0, 5.0, 6.0, 7.0]I have executed the above example code and added the screenshot below.
Handle Multiple Iterables with map() Function in Python
The map function can also handle multiple iterables. When doing so, the function passed to map should accept as many arguments as there are iterables. Here’s an example:
Example 4: Add Corresponding Elements of Two Lists
Suppose you have two lists of numbers and you want to add the corresponding elements of each list:
list1 = [1, 2, 3, 4]
list2 = [10, 20, 30, 40]
def add(x, y):
return x + y
result = list(map(add, list1, list2))
print(result)Output:
[11, 22, 33, 44]Read Is Python a Good Language to Learn?
Use Lambda Functions with map() in Python
Lambda functions are anonymous functions defined using the lambda keyword. They are often used with the map function for simple operations. Here’s an example:
Example 5: Double Numbers
If you want to double each number in a list, you can use a lambda function with map:
numbers = [1, 2, 3, 4, 5]
doubled_numbers = list(map(lambda x: x * 2, numbers))
print(doubled_numbers)Example: Data Transformation for a US-Based Company
Let’s consider a real-world scenario where you’re working for a US-based e-commerce company. You have a list of product prices in different formats (strings, floats, etc.), and you need to convert all prices to floats for further processing. Here’s how you can use the map function to achieve this:
Example 6: Convert Product Prices to Floats
prices = ["19.99", 29.99, "15.49", "23.89", 49.99]
converted_prices = list(map(float, prices))
print(converted_prices)Check out What Is the Best Way to Learn Python?
Combine map() Function with Other Functions
The map a function can be combined with other functions like filter and reduce to perform more complex operations.
Example 7: Filter() and Map() Function in Python
Suppose you have a list of ages and you want to filter out ages below 18 and then calculate the squares of the remaining ages:
ages = [15, 18, 21, 16, 30, 25]
filtered_ages = filter(lambda x: x >= 18, ages)
squared_ages = list(map(lambda x: x ** 2, filtered_ages))
print(squared_ages)Check out How to Use the Python pop() Function?
Conclusion
In this tutorial, I helped you to learn how to use the Python map function in Python. I discussed what is map() function is in Python, we saw how to handle multiple iterables with the map() function in Python, using the lambda function in a map(), a real-time example, and how to combine the map() function with other functions.
You may also like to read:
- How to Use the ceil() Function in Python?
- How to Use the repeat() Function in Python?
- Python / vs //
I am Bijay Kumar, a Microsoft MVP in SharePoint. Apart from SharePoint, I started working on Python, Machine learning, and artificial intelligence for the last 5 years. During this time I got expertise in various Python libraries also like Tkinter, Pandas, NumPy, Turtle, Django, Matplotlib, Tensorflow, Scipy, Scikit-Learn, etc… for various clients in the United States, Canada, the United Kingdom, Australia, New Zealand, etc. Check out my profile.
