What’s the best way to remove duplicates from a Python list of lists? This is a popular coding interview question at Google, Facebook, and Amazon. In this article, I’ll show you how (and why) it works—so keep reading! How to remove all duplicates of a given value in the list? Method 1: Naive Method Algorithm: … Read more
Short answer: You can remove all empty lists from a list of lists by using the list comprehension statement [x for x in list if x] to filter the list. In the following, you’ll learn about the two methods using list comprehension and the filter() function to remove all empty lists from a list of … Read more
Short answer: To print a list of lists in Python without brackets and aligned columns, use the ”.join() function and a generator expression to fill each string with enough whitespaces so that the columns align: I’ll explain this code (and simpler variants) in the following video: As an exercise, you can also try it yourself … Read more
[20-SEC SUMMARY] Given a list of list stored in variable lst. To flatten a list of lists, use the list comprehension statement [x for l in lst for x in l]. To modify all elements in a list of lists (e.g., increment them by one), use a list comprehension of list comprehensions [[x+1 for x … Read more
If you’re in a hurry, here’s the short answer: Use the list comprehension statement [list(x) for x in tuples] to convert each tuple in tuples to a list. This also works for a list of tuples with a varying number of elements. But there’s more to it, and studying the three main methods to achieve … Read more
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 … Read more
For some applications, it’s quite useful to convert a list of lists into a dictionary. Databases: List of list is table where the inner lists are the database rows and you want to assign each row to a primary key in a new dictionary. Spreadsheet: List of list is two-dimensional spreadsheet data and you want … Read more
Say, you want to convert a list of lists lst=[[1, 2], [3, 4]] into a single list [1, 2, 3, 4]. How to achieve this? There are different options: List comprehension [x for l in lst for x in l] assuming you have a list of lists lst. Unpacking [*lst[0], *lst[1]] assuming you have a … Read more
There’s an element of confusion regarding the term “lists of lists” in Python. I wrote this most comprehensive tutorial on list of lists in the world to remove all those confusions by beginners in the Python programming language. This multi-modal tutorial consists of: Source code to copy&paste in your own projects. Interactive code you can … Read more
Problem: Given a Python list with n elements. How to convert it into a tuple with the same n elements? Examples: Note Tuple: Tuples are similar to lists—with the difference that you cannot change the tuple values (tuples are immutable) and you use parentheses rather than square brackets. Solution: Use the built-in Python tuple() function … Read more
Summing up a list of numbers appears everywhere in coding. Fortunately, Python provides the built-in sum() function to sum over all elements in a Python list—or any other iterable for that matter. (Official Docs) The syntax is sum(iterable, start=0): Argument Description iterable Sum over all elements in the iterable. This can be a list, a … Read more
Do you know the best way of removing duplicates from a Python list? This is a popular coding interview question at Google, Facebook, and Amazon. In this article, I’ll show you how (and why) it works—so keep reading! How to remove all duplicates of a given value in the list? Naive Method: Go over each … Read more