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! ChrisWhile working … 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
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
The most Pythonic way to concatenate a list of objects is the expression ”.join(str(x) for x in lst) that converts each object to a string using the built-in str(…) function in a generator expression. You can concatenate the resulting list of strings using the join() method on the empty string as a delimiter. The result … Read more
To join specific list elements (e.g., with indices 0, 2, and 4) and return the joined string that’s the concatenation of all those, use the expression ”.join([lst[i] for i in [0, 2, 4]]). The list comprehension statement creates a list consisting of elements lst[0], lst[2], and lst[4]. The ”.join() method concatenates those elements using the … Read more
To join and replace all strings in a list lst between start index 1 and end index 5, use the one-liner lst[1:5] = [”.join(lst[1:5])]. This solution is based on slice assignment that selects the slice you want to replace on the left and the values to replace it on the right side of the assignment. … Read more
The most efficient method to join a list of Python strings in reverse order is to use the Python code ”.join(l[::-1]). First, reverse the list l using slicing with a negative step size l[::-1]. Second, glue together the strings in the list using the join(…) method on the empty string ”. Problem: Given a list … Read more
Problem: Given a dictionary and a filter condition. How to filter a dictionary by … … key so that only those (key, value) pairs in the dictionary remain where the key satisfies the condition? … value so that only those (key, value) pairs remain where the value satisfies the condition? In this tutorial, you’ll learn … Read more
In this tutorial, you’ll learn the runtime complexity of different Python operations. Then, you’ll learn how to calculate the complexity of your own function by combining the complexity classes of its constituents. This is called “static analysis” The tutorial is loosely based on (source) but it extends it significantly with more practical examples, interactive snippets, … Read more