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
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
Do you want to find the maximum of a Python list? This article gives you everything you need to know to master the max() function in Python. Description Python’s built-in max() function returns the maximum element of a list or its generalization (an iterable). Syntax The syntax of the max() function is as follows: Arguments … Read more
Summary: There are only three best ways to reverse the order of the list elements: list.reverse() — Best if you want to reverse the elements of list in place. list[::-1] — Best if you want to write concise code to return a new list with reversed elements. reversed(list) — Best if you want to iterate … Read more
Summary: To convert a dictionary to a list of tuples, use the dict.items() method to obtain an iterable of (key, value) pairs and convert it to a list using the list(…) constructor: list(dict.items()). To modify each key value pair before storing it in the list, you can use the list comprehension statement [(k’, v’) for … Read more
Problem: Given are two lists l1 and l2. You want to perform either of the following: 1. Boolean Comparison: Compare the lists element-wise and return True if your comparison metric returns True for all pairs of elements, and otherwise False. 2. Difference: Find the difference of elements in the first list but not in the … Read more
Short answer: The most Pythonic way to compute the difference between two lists l1 and l2 is the list comprehension statement [x for x in l1 if x not in set(l2)]. This works even if you have duplicate list entries, it maintains the original list ordering, and it’s efficient due to the constant runtime complexity … Read more
To check if two unordered lists x and y are identical, compare the converted sets with set(x) == set(y). However, this loses all information about duplicated elements. To consider duplicates, compare the sorted lists with sorted(x) == sorted(y). Due to the efficient merge-sort-like implementation of the sorted() function, this is quite fast for almost-sorted lists. … Read more
The most Pythonic way to check if two ordered lists l1 and l2 are identical, is to use the l1 == l2 operator for element-wise comparison. If all elements are equal and the length of the lists are the same, the return value is True. Problem: Given are two lists l1 and l2. You want … Read more
Answer: The simplest, most straightforward, and most readable way to convert a tuple to a list is Python’s built-in list(tuple) function. You can pass any iterable (such as a tuple, another list, or a set) as an argument into this so-called constructor function and it returns a new list data structure that contains all elements … Read more