To get the number of elements in a Python list, use the len(list) function. You don’t need to import any external library because len() is a Python built-in function. You can use it to get the number of elements of several built-in and library types in Python such as tuples and sets. Here’s the minimal … Read more
If you’ve already learned how to make basic 3d plots in maptlotlib and want to take them to the next level, then look no further. In this article, I’ll teach you how to create the two most common 3D plots (surface and wireframe plots) and a step-by-step method you can use to create any shape … 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
When does the IndexError: list assignment index out of range appear? Python throws an IndexError if you try to assign a value to a list index that doesn’t exist, yet. For example, if you execute the expression list[1] = 10 on an empty list, Python throws the IndexError. Simply resolve it by adding elements to … Read more
Problem: Given a list of strings. How to convert the list to a string by concatenating all strings in the list? Example: You want to convert list [‘learn ‘, ‘python ‘, ‘fast’] to the string ‘learn python fast’. Solution: to convert a list of strings to a string, do the following. Call the ”.join(list) method … Read more
[Spoiler] Which function filters a list faster: filter() vs list comprehension? For large lists with one million elements, filtering lists with list comprehension is 40% faster than the built-in filter() method. To answer this question, I’ve written a short script that tests the runtime performance of filtering large lists of increasing sizes using the filter() … Read more
Nested List Comprehension—what does it even mean? There are three equally interpretations of this term: Coming from a computer science background, I was assuming that “nested list comprehension” refers to the creation of a list of lists. In other words: How to create a nested list with list comprehension? But after a bit of research, … Read more
How can you filter a list in Python using an arbitrary condition? The most Pythonic and most performant way is to use list comprehension [x for x in list if condition] to filter all elements from a list. Filter with List Comprehension The most Pythonic way of filtering a list—in my opinion—is the list comprehension … Read more
In this article, you’ll learn how to filter a list of dictionaries. So let’s get started! Short answer: The list comprehension statement [x for x in lst if condition(x)] creates a new list of dictionaries that meet the condition. All dictionaries in lst that don’t meet the condition are filtered out. You can define your … Read more
The release of Python 3.8 came with an exciting new feature: the Walrus Operator. It’s an assignment expression, or in simpler terms an assignment inside an expression. Let’s dive into practice immediately and look at the following code: We have a list of users whose data is represented in a dictionary. We want to count … Read more
Here’s your free PDF cheat sheet showing you all Python list methods on one simple page. Click the image to download the high-resolution PDF file, print it, and post it to your office wall: I’ll lead you through all Python list methods in this short video tutorial: If you want to study the methods yourself, … Read more
That’s a very common question and the answer is: It depends.It depends on the data in the list and how you want it to be represented in the dictionary. In this article we go over six different ways of converting a list to a dictionary. You can also watch my advanced one-liner video where we … Read more