Problem: Given a dictionary and a key. Can you use the ternary operator to return the key from the dictionary, but only if it exists to avoid the key error? If the key doesn’t exist, a “fall-back” function should be executed. Example: Say, you want to do something like the following (pseudocode): Ternary Operator Short … Read more
Do you want to learn Python but you’re overwhelmed and you don’t know where to start? Learn with Python cheat sheets! They compress the most important information in an easy-to-digest 1-page format. Here’s the new Python cheat sheet I just created—my goal was to make it the world’s most concise Python cheat sheet!
You may know the ternary operator x if c else y in Python which reads as “return x if c else return y“. But you may not know that you can also write the ternary operator in a shorter form as (y, x)[c]. Let’s dive into this concise way of hacking your own ternary operator! … Read more
In this one-liner tutorial, you’ll learn about the popular sorting algorithm Quicksort. Surprisingly, a single line of Python code is all you need to write the Quicksort algorithm! Problem: Given a list of numerical values (integer or float). Sort the list in a single line of Python code using the popular Quicksort algorithm! Example: You … Read more
This is a running document in which I’ll answer all questions regarding the single line of Python code. If you want to become a one-liner wizard, check out my book “Python One-Liners”! 🙂 This document contains many interactive code shells and videos to help you with your understanding. However, it’s pretty slow because of all … Read more
Problem: Say, you have a dictionary {0: ‘Alice’, 1: ‘Bob’} and you want to create a list of dictionaries with copies of the original dictionary: [{0: ‘Alice’, 1: ‘Bob’}, {0: ‘Alice’, 1: ‘Bob’}, {0: ‘Alice’, 1: ‘Bob’}]. You use list comprehension with a “throw-away” loop variable underscore _ to create a list of 3 elements. … Read more
Short answer: Per default, the zip() function returns a zip object of tuples. To obtain a list of lists as an output, use the list comprehension statement [list(x) for x in zip(l1, l2)] that converts each tuple to a list and stores the converted lists in a new nested list object. Intermediate Python coders know … Read more
In this article, I’ll explain the np.linspace function, how to use it and when you should. It has got a bit of a reputation for being complicated but, as you’ll see, it really isn’t! So, let’s get a quick overview first. Syntax: numpy.linspace(start, stop, num=50, endpoint=True, retstep=False, dtype=None, axis=0) Argument Default Description start – The … Read more
Do you want to initialize a list with some random numbers? In this article, I’ll show you four different way of accomplishing this—along with a short discussion about “the most Pythonic way”. Problem: Given an integer n. Create a list of n elements in a certain interval (example interval: [0, 20]). Solution: Here’s a quick … Read more
To create a list of n placeholder elements, multiply the list of a single placeholder element with n. For example, use [None] * 5 to create a list [None, None, None, None, None] with five elements None. You can then overwrite some elements with index assignments. In the example, lst[2] = 42 would result in … Read more
What’s SymPy Anyway? SymPy is a Python library for symbolic computation. So instead of approximating the result of the square root of 2, it keeps the square root intact—using a symbolic representation. This helps in further processing and can lead to situations where Python has introduced a floating point precision error without need. Here’s a … Read more
To install SymPy in Python, simply run the following command in your shell: This works for all major operating systems (MacOS, Windows, Linux). A preliminary is to have the pip package manager installed. (Confused by all the libraries, modules, pip, and virtual environments? Read the ultimate library guide on my blog.) To check whether it … Read more