If you’re in a hurry, here’s the short answer: use the list comprehension statement
[tuple(x) for x in list] to convert each element in your
list to a tuple. This works also for list of lists with varying number of elements.
But there’s more to it and studying the two main methods to achieve the same objective will make you a better coder. So keep reading:
Method 1: List Comprehension + tuple()
Problem: How to convert a list of lists into a list of tuples?
Example: You’ve got a list of lists
[[1, 2], [3, 4], [5, 6]] and you want to convert it into a list of tuples
[(1, 2), (3, 4), (5, 6)].
lst = [[1, 2], [3, 4], [5, 6]] tuples = [tuple(x) for x in lst] print(tuples) # [(1, 2), (3, 4), (5, 6)]
Try It Yourself:
This approach is simple and effective. List comprehension defines how to convert each value (
x in the example) to a new list element. As each list element is a new tuple, you use the constructor
tuple(x) to create a new tuple from the list
If you have three list elements per sublist, you can use the same approach with the conversion:
lst = [[1, 2, 1], [3, 4, 3], [5, 6, 5]] tuples = [tuple(x) for x in lst] print(tuples) # [(1, 2, 1), (3, 4, 3), (5, 6, 5)]
You can see the execution flow in the following interactive visualization (just click the “Next” button to see what’s happening in the code):
And if you have a varying number of list elements per sublist, this approach still works beautifully:
lst = [, [2, 3, 4], [5, 6, 7, 8]] tuples = [tuple(x) for x in lst] print(tuples) # [(1,), (2, 3, 4), (5, 6, 7, 8)]
You see that an approach with list comprehension is the best way to convert a list of lists to a list of tuples. But are there any alternatives?
Method 2: Map Function + tuple()
An alternative is to use the map function that applies a specified function on each element of an iterable. Guido van Rossum, the creator of Python, didn’t like the
map() function as it’s less readable (and less efficient) than the list comprehension version (method 1 in this tutorial). You can read about a detailed discussion on how exactly he argued on my blog article.
So, without further ado, here’s how you can convert a list of lists into a list ot tuples using the
lst = [, [2, 3, 4], [5, 6, 7, 8]] tuples = list(map(tuple, lst)) print(tuples) # [(1,), (2, 3, 4), (5, 6, 7, 8)]
Try it yourself:
The first argument of the
map() function is the
tuple function name. This
tuple() function converts each element on the given iterable
lst (the second argument) into a tuple. The result of the
map() function is an iterable so you need to convert it to a list before printing it to the shell because the default string representation of an iterable is not human-readable.
- List of Lists
- How to Convert a List of Tuples to a List of Lists
- How to Convert a List of Lists to a Pandas Dataframe
- How to Convert a List of Lists to a NumPy Array
- How to Convert a List of Lists to a Dictionary in Python
Where to Go From Here?
Enough theory. Let’s get some practice!
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While working as a researcher in distributed systems, Dr. Christian Mayer found his love for teaching computer science students.
To help students reach higher levels of Python success, he founded the programming education website Finxter.com. He’s author of the popular programming book Python One-Liners (NoStarch 2020), coauthor of the Coffee Break Python series of self-published books, computer science enthusiast, freelancer, and owner of one of the top 10 largest Python blogs worldwide.
His passions are writing, reading, and coding. But his greatest passion is to serve aspiring coders through Finxter and help them to boost their skills. You can join his free email academy here.