Concatenating two lists in Python

Lists in Python can be concatenated in two ways

1. Using + operator
2. Using extend

Let list_a and list_b be defined as below

list_a = [1, 2, 3, 4]
list_b = [5, 6, 7, 8]

Using + operator to concatenate two list_a and list_b

list_c = list_a + lis_b 
print list_c # Output: [1, 2, 3, 4, 5, 6, 7, 8]

If we do not want a new list i.e. list_c

list_a = list_a + list_b
print list_a # Output: [1, 2, 3, 4, 5, 6, 7, 8]

Using extend

extend operator can be used to concatenate one list into another. It is not possible to store the value into the third list. One of the existing list has to store the concatenated result.

Want to read this story later? Save it in Journal.

list_c = list_a.extend(list_b)
print list_c # Output: NoneType
print list_a # Output: [1, 2, 3, 4, 5, 6, 7, 8]
print list_b # Output: [5, 6, 7, 8]

In the above example, extends concatenates the list_b into list_a

Which is better?

We can use either of the ways to concatenate the list. There is not much difference in performance. + operators seems to be slightly better. But this difference will be visible only when the concatenation is done a very large number of times

If you like my articles and find them useful, feel free to buy me a coffee. Thanks!

To get updates for my new stories, follow me on medium and twitter

Other articles:

1. Beginner’s Guide to ReactJS
2. The Journey of JavaScript: from Downloading Scripts to Execution
3. Why Progressive Web Apps are great and how to build one
4. Let’s get this ‘this’ once and for all
5. Service Workers
6. Service Workers implementation
7. Execution Context in JavaScript
8. Virtual DOM in ReactJS
9. Prototypes in JavaScript
10. ‘this’ in JavaScript
11. Object.create in JavaScript
12. Inheritance in JavaScript
13. Create objects in JavaScript
14. Objects in JavaScript
15. Zip in Python
16. decorators in Python
17. Concatenating two lists in Python
18. lambda, map, and filter in Python
19. List comprehensions in Python

📝 Read this story later in Journal.

👩‍💻 Wake up every Sunday morning to the week’s most noteworthy stories in Tech waiting in your inbox. Read the Noteworthy in Tech newsletter.