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
Want to convert two lists into a dictionary? Do the following: Zip the lists together using zip(list_1, list_2). Create a dictionary from the list of tuples using the constructor dict() on the result. In other words, call dict(zip(list_1, list_2)) to convert two lists into a dictionary. Try it yourself: Let’s dive into the code step-by-step. … Read more
Want to calculate the standard deviation of a column in your Pandas DataFrame? In case you’ve attended your last statistics course a few years ago, let’s quickly recap the definition of variance: it’s the average squared deviation of the list elements from the average value. You can do this by using the pd.std() function that … Read more
Imagine the following scenario: You work in law enforcement for the US Department of Labor, finding companies that pay below minimum wage so you can initiate further investigations. Like hungry dogs on the back of a meat truck, your Fair Labor Standards Act (FLSA) officers are already waiting for the list of companies that violated … Read more
This article shows you how to calculate the variance of a given list of numerical inputs in Python. In case you’ve attended your last statistics course a few years ago, let’s quickly recap the definition of variance: it’s the average squared deviation of the list elements from the average value. So, how to calculate the … Read more
Don’t Be Mean, Be Median. This article shows you how to calculate the average of a given list of numerical inputs in Python. In case you’ve attended your last statistics course a few years ago, let’s quickly recap the definition of the average: sum over all values and divide them by the number of values. … Read more
Some coders possess laser-like code understanding skills. They look at a piece of source code, and the meaning pops immediately into their great minds. If you present them with a new code snippet, they’ll tell you in a few seconds what it does. Since I’ve started to train this skill of rapid code understanding in … Read more
This is a tutorial video from my new book “Python One-Liners” with NoStarch press (San Francisco 2020). Grab your Python One-Liner Superpower now! (Amazon Link) Here’s the code that shows you how to sample a two-dimensional Python list—including only every other list element in the resulting two-dimensional Python list. All of this happens in a … Read more
The runtime complexity of the len() function on your Python list is O(1). It takes constant runtime no matter how many elements are in the list. Why? Because the list object maintains an integer counter that increases and decreases as you add and remove list elements. Looking up the value of this counter takes constant … Read more