ChrisPython’s dictionary data structure is one of the most powerful, most underutilized data structures in Python. Why? Because checking membership is more efficient for dictionaries than for lists, while accessing elements is easier for dictionaries than for sets. In this tutorial, you’ll learn how to perform four common dictionary operations in one line of Python … Read more
Problem: How to append elements to a list using a single line for loop? Example: You hope to accomplish something like this where you create an initial list (this one is empty) and you append multiple elements to it: However, this statement doesn’t work! Is there a one-line for loop to append elements to a … Read more
Dictionary Comprehension is a concise and memory-efficient way to create and initialize dictionaries in one line of Python code. It consists of two parts: expression and context. The expression defines how to map keys to values. The context loops over an iterable using a single-line for loop and defines which (key,value) pairs to include in … Read more
Here’s the step-by-step approach of how to deploy your Dash app on Pythonanywhere.com using Flask and pip: Create an account on Pythonanywhere.com. Create a Flask application. Create a Dash application. Copy the Dash app into the Flask app. Connect the Flask server with the Dash app. Modify the WSGI configuration file. Install Dash with pip … Read more
Can you believe it? People use unknown and potentially insecure websites to generate their random passwords! This works as follows: A website generates a “random” password for them and they copy&paste it and assume this is a safe password because of the randomness of the characters. What a security flaw! Why? Because the website could … Read more
A generator function is a Pythonic way to create an iterable without explicitly storing it in memory. This reduces memory usage of your code without incurring any additional costs. The following code shows a function get_numbers(n) that returns a list of n random numbers. However, this is not very efficient code because you create a … Read more
Problem: How to match dollar amounts in a given string? If cent amounts are given, those should match as well. Solution: You can use regular expression pattern ‘(\$[0-9]+(.[0-9]+)?)’ to find all numbers that start with a dollar symbol, followed by an arbitrary number of numerical digits, followed by an optional decimal point and an arbitrary … Read more
To update a global variable in one line of Python, retrieve the global variable dictionary with the globals() function, and access the variable by passing the variable name as a string key such as globals()[‘variable’]. Then overwrite the global variable using the equal symbol, for example in globals()[‘variable’] = 42 to overwrite the variable with … Read more
This tutorial is a chapter excerpt drafted for my new book “Python One-Liners” (to appear in 2020, No Starch Press, San Francisco). Are you an office worker, student, software developer, manager, blogger, researcher, author, copywriter, teacher, or self-employed freelancer? Most likely, you are spending many hours in front of your computer, day after day. In … Read more
Wouldn’t reading code be much easier if the author constantly shared their thoughts with you? Commenting is good practice in Python because it helps others (and your future self) understanding your code much better. Writing commented code makes you more productive in the long term! There are two types of comments: one-line comments and multi-line … Read more
Do you hate those lengthy class definitions with __init__ and too many whitespaces and newlines? Python One-Liners to the rescue! Luckily, you can create classes in a single line—and it can even be Pythonic to do so! Sounds too good to be true? Let’s dive right into it! Problem: How to create a Python class … Read more
In this article, you’ll learn about two variants of this problem. Assign multiple values to multiple variables Assign the same value to multiple variables Let’s have a quick overview of both in our interactive code shell: Exercise: Increase the number of variables to 3 and create a new one-liner! Let’s dive into the two subtopics … Read more