Challenge: How to create a multi-line string in Python? In this tutorial, I’ll show you four methods to create and maintain multi-line strings in Python. The most Pythonic ones are the first two methods with triple single quotes ”’ … ”’ or triple double quotes “”” … “”” that wrap a string across multiple lines. … Read more
This tutorial introduces an advanced language feature: lambda functions. Lambda functions are rooted in the mathematical area of lambda calculus. One of the pioneers of this area was Alonzo Church. He introduced lambda functions in 1936 even before the appearance of the first computers. Lambda functions exist in a wide range of languages for functional … Read more
Modifying a sequence while iterating over it can cause undesired behavior due to the way the iterator is build. To avoid this problem, a simple solution is to iterate over a copy of the list. For example, you’ll obtain a copy of list_1 by using the slice notation with default values list_1[:]. Because you iterate … Read more
Challenge: How to find a given value in a sorted list? Example: Say, you have a sorted list: Your goal is to find the index of the element 103 in the list. Do you have to check all elements to do this? Well, only if you used the … Naive List Search Algorithm A naive … Read more
Problem: Write a function that joins an arbitrary number of string arguments with a given separator. Example: Given the string arguments “A”, “B”, and “C” and the string separator “-“. Join them to the concatenated string “A-B-C”. Solution: The following code creates a Python function concat() that takes an arbitrary number of arguments, packs them … Read more
The bubble sort does exactly what you’d expect it to do. It sorts an input list by treating each element as a bubble that climbs up the list. Each bubble rises as long as it is greater than the list elements. If a list element is smaller or equal to a list element, the bubble … Read more
Challenge: How to find an element in a sorted matrix where row and column values increase monotonically? What is a matrix? A matrix is a table of values consisting of rows and columns. Here, we represent the matrix as a list of integer lists. Hence, we can access matrix values with the indexing and slicing … Read more
The Fibonacci series was discovered by the Italian mathematician Leonardo Fibonacci in 1202 and even earlier by Indian mathematicians. The series appears in unexpected areas such as economics, mathematics, art, and nature. Algorithm Sketch In the following, we give a simple algorithm to calculate the Fibonacci numbers. The series starts with the Fibonacci numbers zero … Read more
This tutorial introduces the concept of default arguments in Python. A default argument is a function argument that takes on a default value if you don’t pass an explicit value for when calling the function. For example, the function definition def f(x=0): <body> allows you to call it with or without the optional argument x—valid … Read more
String slicing is a concept to carve out a substring from a given string. Use slicing notation s[start:stop:step] to access every step-th element starting from index start (included) and ending in index stop (excluded). All three arguments are optional, so you can skip them to use the default values (start=0, stop=len(string), step=1). For example, the … Read more
An arbitrary argument list is a Python feature to call a function with an arbitrary number of arguments. It’s based on the asterisk “unpacking” operator *. To catch an arbitrary number of function arguments in a tuple args, use the asterisk syntax *args within your function definition. For example, the function def f(*args): … allows … Read more
Challenge: Given is function f. How to assign the function to variable g, so that you can call g() and it runs function f()? Your desired output is function f‘s output: How to accomplish this in the most Pythonic way? Overview: We examine two methods to accomplish this challenge. You can run them in our … Read more