Python 3’s asyncio module provides fundamental tools for implementing asynchronous I/O in Python. It was introduced in Python 3.4, and with each subsequent minor release, the module has evolved significantly. This tutorial contains a general overview of the asynchronous paradigm, and how it’s implemented in Python 3.7. Blocking vs Non-Blocking I/O The problem that asynchrony seeks to resolve is blocking I/O. By default, when your program accesses data from an I/O source, it waits for that operation to complete before […]

In this article, we’ll examine how to append content to an existing file using Python. Let’s say we have a file called helloworld.txt containing the text “Hello world!” and it is sitting in our current working directory on a Unix file system: $ cat ./helloworld.txt Hello world! Now assume we want to append the additional text “It’s good to have been born!” to the end of this file from a Python program. The first step is to obtain a reference […]

In this article, we’ll examine four ways to use Python to check whether a string contains a substring. Each has their own use-cases and pros/cons, some of which we’ll briefly cover here: 1) The in Operator The easiest way to check if a Python string contains a substring is to use the in operator. The in operator is used to check data structures for membership in Python. It returns a Boolean (either True or False) and can be used as […]

In this article, we’ll examine how to use the built-in Python zip() function. The zip() function is a Python built-in function that allows us to combine corresponding elements from multiple sequences into a single list of tuples. The sequences are the arguments accepted by the zip() function. Any number of sequences can be supplied, but the most common use-case is to combine corresponding elements in two sequences. For example, let’s say we have the two lists below: >>> vehicles = […]

In this article, we’ll examine how to strip characters from both ends of a string in Python. The built-in String type is an essential Python structure, and comes with a built-in set of methods to simplify working with text data. There are many situations in which a programmer may want to remove unwanted characters, i.e. strip certain characters, from either the beginning or ending of a string. The most common requirement is to strip whitespace (spaces, tabs, newline characters, etc.) […]