Índex per Tech Guru Guide: Coding Academy 2016 a Coding Academy 2015

Programming is more than just a hobby, or a job, or a means to an end. Programming has helped me transform my brain. It’s brought out inner logic and organisation, it’s made me more rational and efficient and, since first picking it up at a very early age, it’s given me a tendency to think in IF...THEN arguments. Don’t judge me, I can’t help it. Whether you’re a dyed-in-the-wool coding type or a beginner hoping to get started and produce your first programming projects, there should be something for you in Coding Academy 2016. We’ve consulted with a host of respected experts in its construction, and forced them to use language (and languages) understandable by mere mortals in their approach. We concentrate mainly on Python, that most human-readable of languages,…

In the previous few tutorials, we have been looking at data. First, we introduced some of Python’s core data types, and then we demonstrated how they can be put to use when solving a real problem. The next data-related topic we want to consider is abstraction, but before we get on to that, we’re first going to look at abstraction – both in general and as it applies to procedures. So, this time we’ll take a brief hiatus from data, before returning to it in a later article. Square roots To get our heads around the concept of abstraction, let’s start by thinking about square roots and different techniques for finding them. One of these was discovered by Newton, and is thus known as Newton’s method. Newton’s method states that…

The previous tutorial showed you how to build a simple cat clone in Python. In this guide, we’re going to add some more features to our program, including the ability to read from the standard input pipe, just like the real cat, and the ability to pass options to your cat clone. So, without further delay, let’s dive in. Fortunately, you already know everything you need to interact with the standard input pipe. In Linux, all pipes are treated like files – you can pass a file as an argument to a command, or you can pass a pipe as an argument. It doesn’t matter which you do, because they’re basically the same thing. In Python, the same is true. All you need to get to work with the standard…

Storage is cheap: you can buy a 500GB external hard drive for less than £35 these days, while even smartphones come with at least 8GB of storage, and many are easily expandable up to 64GB for only the price of a pair of jeans. It’s no surprise, then, that almost every modern application stores data in one way or another, whether that’s configuration data, cached data to speed up future use, saved games, to-do lists or photos. The list goes on and on. With this in mind, this programming tutorial is going to demonstrate how to deal with persistent data in our language of choice – Python. The most obvious form of persistent storage that you can take advantage of in Python is file storage. Support for it is included…

Audio is an important means of communication and, truth be told, working with multimedia is fun. However, working with audio is a challenging task because it involves handling a variety of devices, standards and formats. There are several libraries that you can use with Python to capture and manipulate sound, and make interactive apps. One of the better platform-independent libraries to make sound work with your Python application is PyAudio. The library can help you record audio as well as play back sounds without writing oodles of code. The PyAudio library provides Python bindings for the popular cross-platform PortAudio I/O library. It can be easily installed with a simple pip install pyaudio command. As with all programs, you need to begin any PyAudio program by importing the library. PyAudio is…

Being able to automatically process text can save you time and energy. So let’s learn how to efficiently work with text files by picking up the basics of text processing in Python, including search and replace using regular expressions, converting a date format to another, and developing a graphical interface to make life easier. As you might be aware, two Python versions are currently being used. This tutorial uses the “older” version (Python version 2.7.x) but you will have no problem following this tutorial if you are using version 3. Basic Information The following Python code, saved as lBl.py, shows how to process a text file line by line in Python which is the foundation of text processing: The following Python code, saved as lines.py, counts the number of lines…

Quick tip For experimenting with compatibility between different versions of MySQL/MariaDB, checkout the handy MySQL Sandbox: http://mysqlsandbox.net The MySQL RDBMS (Relational database management system) first appeared on the scene in 1995, and its then custodian, Swedish firm MySQL AB, became one of the earliest examples of a successful open source company. While the database was entirely available under the GPL, clients unwilling to pander to its clauses (ie those who wanted to implement MySQL databases in closedsource products) could acquire the software under a monetary licence. In 2008, MySQL AB was acquired by Sun Microsystems, giving them a competitor to arch rival Oracle's database. However, two years hence, Sun was acquired by Oracle, so that MySQL was now, in a sense, in the hands of the enemy. As one may…

This tutorial will use the MongoDB knowledge you already have and combine it with Bottle, a Python framework, in order to create a blog site that stores its data on a MongoDB database. The Bottle framework will be mainly responsible for the user interface of the website as well as its logic. We’re assuming that you’ll have both MongoDB and PyMongo already installed on your Linux distro. If you don’t feel comfortable with MongoDB and PyMongo – the Python MongoDB driver – we’d recommended revisiting the articles on the previous few pages to learn more about using the driver and MongoDB administration, respectively). At the end of this tutorial, you’ll have a beautiful blog site written in Python that uses MongoDB to store its data and Bottle to display it.…

Git is a distributed source code and versioning management tool, though in many ways it's closer to a file system than it is to other versioning systems, such as CVS and Mercurial. Code is stored in a (local or remote) repository. Users with the relevant permissions may clone this repository to their own local working directory, and thereafter will have access to not only the latest master branch of the source code, but all other branches, and all of their histories. They can make changes, commit them to their local repository and if necessary file a pull request to have those changes incorporated into the project. Since very soon after its release, Git has been self-hosted – its source code is managed through a Git repository, too. Sourcery, we say.…

Murray Walker, the great Formula 1 commentator, used to say “IF is F1 spelled backwards.” Ifs, buts and maybes play a vital role in motor racing, as they do in computer programming. If you’re writing a program that simply processes and churns out a bunch of numbers, without any user interaction, then you might be able to get away without any kind of conditional statements. But most of the time, you’ll be asking questions in your code: if the user has pressed the [Y] key, then continue. If not, stop. Or if the variable PRICE is bigger than 500, halt the transaction. And so forth. A condition is just a question, as in everyday life: if the kettle has boiled, turn off the gas. (We don’t use newfangled electricity around…

We’ve come quite a long way over the last two tutorials, having implemented the ability to echo the contents of multiple files to the screen, the ability to echo standard input to the screen and the ability to detect and act upon options passed by the user of our program. All that remains is for us to implement the line number option and to gather together everything else we’ve written into a single, working program. Objects Last time, we ended by saying that there are many ways we could implement the line counting option in our program. We’re going to show you how to do it in an object-oriented style, because it gives us an excuse to introduce you to this aspect of Python programming. You could, however, with a…

“The first rule of data encryption is this: never to try to create your own.” When writing a program, we usually assume that the other applications are friendly. We don’t normally try to hide our data from them. In fact, we normally try to write our files so that other programs can read them. We use text encodings, XML and other standards to make sure that our files play nicely with other software. However, there are times when we want to keep our information to ourselves. Perhaps we need to transmit it across an insecure network, or put it on a USB key that could be lost. Whatever the case, we need to make sure that prying eyes can’t see what it is, and for this we use encryption. Before…

We’ve done all kinds of introductory level programming in the office, hacking around with Minecraft, ancient board games in Python, word games in PHP [do all our writers just play games all day? – Ed]. But these tend to be either console-based text only affairs, or dependent on some prefabricated graphical interface. Surely it must be possible to make your own? Most of the graphical applications (the ones that run in their own windows at least) you’ll come across on Linux fall into two camps Qt (pronounced ‘cute’) and GTK (pronounced… [Oh, get on with it – Ed]). These are the two different toolkits around which KDE and Gnome, respectively, applications are built. The venerable, but full of bugs, version 2 of GTK has been largely succeeded by version 3,…

Quick tip Scroll through Tweepy’s documentation (http://docs. tweepy.org/en/latest/api. html) for a list of supported methods Twitter is a wonderful tool if you want to get a feel for what the world is thinking. The visible 140-character social network is powered by a wonderful API that enables users to drink from the firehose and capture all the raw data passing over the network. Once captured, you can use this data to mine all kinds of meaningful information. You can, for example, find trends related to specific keywords or gauge sentiments during events. Tweepy is one of the easiest libraries that you can use to access the Twitter API with Python. In this tutorial, we’ll be using Tweepy to capture any tweets that mention OggCamp, and then we’ll mine the data to…

This article is an introduction to drawing with the help of Python version 3.4.x. However, depending on your Linux system, you might have Python version 3.5.x which will not make any real difference; If you’re using version 2.7.x of Python then some of the presented scripts might need small changes in order to run. Almost all modules related to drawing and plotting work in a similar way: you first define an object which will be the “owner” of all other objects and then you add various elements to it which can be points, lines, squares, etc. You can grab all the source code from http://bit.ly/1RZp1WS. A simple Python example The graphics module can be used to generate simple graphics, and it works with both Python versions. On Ubuntu Linux, download…

Legend tells of one Sissa ibn Dahir who invented the game of Chess for an Indian king. So impressed was that king that he offered Sissa anything he desired as a reward. Being of a calculating bent, Sissa replied “Then I wish that one grain of wheat shall be put on the first square of the chessboard, two on the second, and that the number of grains shall be doubled until the last square is reached: whatever the quantity this might be, I desire to receive it”. The king soon realised that there was not enough wheat in the world to fulfil this demand, and once again was impressed. There are various endings to this story, in one Sissa is given a position within the king’s court, in another he…

NoSQL databases are designed for the web and don’t support joins, complex transactions and other features of the SQL language. MongoDB is an open source NoSQL database written in C++ by Dwight Merriman and Eliot Horowitz which has native drivers for many programming languages, including C, C++, Erlang, Haskell, Perl, PHP, Python, Ruby and Scala. In this tutorial, we’ll cover the MongoDB drivers for Python and Ruby. The MongoDB document format is based on JSON, and the JSON structures consist of key and value pairs and can nest arbitrarily deep. If you’re not already familiar with JSON, you can think of JSON documents as dictionaries and hash maps that are supported by most programming languages. The following instructions will help you install MongoDB on an Ubuntu Linux system The last…

Quick tip Parentheses for if statements are optional, because Swift considers that sometimes they add unnecessary noise to code. Swift also doesn’t have .h files because you don’t need them. The biggest surprise of the Apple Worldwide Developer Conference 2014 (WWDC) was the announcement of Swift, a new programming language that will – eventually – replace Apple Objective-C. The biggest surprise of WWDC 2015 was the announcement that Swift was to become an open source project. This tutorial is a gentle introduction to Swift and its various features through a few small but complete code examples. It’s most likely, you will find the installation process the most difficult part of this tutorial. Apple doesn’t provide packages for every Linux distribution (distro). Currently, only Ubuntu 14.04 and 15.10 are officially supported.…

PHP might not be pretty, but it sure is useful and anything that can make developing and learning PHP can only be a good thing. We’re going to discover how using a complete VM from scratch, will be able to deliver web pages, run PHP scripts and deliver email. On top of that, we’ll show you how to clone a virtual machine and transfer it to another machine, regardless of whether or not the host or guest is 32-bit or 64-bit. The entire assembly will be discussed from the download of the latest Ubuntu, installing Virtualbox on Ubuntu, installing packages and modifying packages. Although this lesson focuses on Virtualbox, there are virtualisation alternatives, such as KVM, VMware and Xen. Virtual machines can be quite convenient and versatile. For example, you…

Python is a great language. You’re happily writing a little program, and you’ve got a huge list that you need to put in order. What do you do? Easy, just call the sort() method on the list, and you’re away. It works amazingly quickly, and it doesn’t even care how big the list is – it could be millions of elements long and still take virtually the same amount of time to return the sorted list. This is really handy, but have you ever stopped to wonder how on earth it works? It’s a fascinating question, and in the next two articles we’re going to introduce you to some of the techniques that are used to solve this kind of problem. Along the way, you’ll also get a gentle introduction…

In the previous tutorial, we introduced Python’s most common data types: numbers (ints and floats), strings, lists, tuples and dictionaries. We demonstrated how they work with different operators, and explained a few of their most useful methods. We didn’t, however, give much insight into how they might be used in real situations. In this article, we’re going to fix that. We’re going to write a program that counts the number of times each unique word occurs in a text file. Punctuation marks will be excluded, and if the same word occurs but in different cases (for example, the and The), they will be taken to represent a single word. Finally, the program will print the results to the screen. It should look like this: As an example, we’ll be using…

“You now know more than enough to start writing real programs” In the next few pages, that’s what we’re aiming to do: get you writing real programs. Over the next few tutorials, we’re going to create a Python implementation of the popular Unix tool cat. Like all Unix tools, cat is a great target because it’s small and focused on a single task, while using different operating system features, including accessing files, pipes and so on. This means it won’t take too long to complete, but will also expose you to a selection of Python’s core features in the Standard Library, and once you’ve mastered the basics, it’s learning the ins-and-outs of your chosen language’s libraries that will let you get on with real work. Our goal for the project…

In our previous tutorials, we have mentioned how programming is all about managing complexity, and we’ve introduced you to quite a few of the tools and techniques that help programmers do this. From variables to function definitions or object-orientation, they all help. One tool we’ve yet to cover, in part because you don’t start to come across it until you’re writing larger programs, is the idea of modules and name spaces. Yet, if you’ve written a program of any length, even just a few hundred lines, this is a tool you’re no doubt desperate for. In a long file of code, you’ll have noticed how quickly it becomes more difficult to read. Functions seem to blur into one another, and when you’re trying to hunt down the cause of the…

Way back in December 2008, Python 3.0 (also known as Py3k or Python 3000) was released. Yet here we are, eight years later, and most people are still not using it. For the most part, this isn't because Python programmers and distribution maintainers are a bunch of laggards, and the situation is very different from, for example, people's failure/refusal to upgrade (destroy?) Windows XP machines. For one thing, Python 2.7, while certainly the end of the 2.x line, is still regularly maintained, and probably will continue to be until 2020. Furthermore, because many of the major Python projects (also many, many minor ones) haven't been given the 3 treatment, anyone relying on them is forced to stick with 2.7. Early on, a couple of big projects – NumPy and Django…

Python’s multimedia prowess extends to images and includes mechanisms for manipulating snapshots in a variety of ways. While it can be done manually, using Python enables you to automate the process by easily writing scripts to act on a disk full of images and carry out extensive modifications based on a complex set of rules. The Python Image Library, commonly referred to as PIL, was a popular and powerful Python library for handling images. But it hasn’t been updated for over half a decade, and doesn’t support Python 3. Pillow is a fork of PIL that’s based on the PIL code, and has evolved to be a better, modern and more friendly version of PIL. With Pillow, you can open, manipulate and save in all the popular image file formats.…

Quick tip The code in this tutorial is based on vegaseat’s Updated Tiny Tkinter Calculator, listed on DaniWeb.com (tinyurl.com/h3eotvf). Python provides various options for developing graphical user interfaces, such as wxPython, JPython and Tkinter. Of these, Tkinter is the standard GUI library that ships by default with Python. Tkinter is the Python interface to Tk, the GUI toolkit for Tcl/Tk. Tk was developed as a GUI extension for the Tcl scripting language in the early 1990s. One of the reasons for its popularity is that it’s easier to learn than other toolkits. Tkinter provides a powerful object-oriented interface to the Tk GUI toolkit. To use Tkinter, you don’t need to write Tcl code, because Tkinter is a set of wrappers that implement the Tk widgets as Python classes. Creating a…

Developing concurrent applications is a difficult subject and threads are the root of many nasty bugs, so you should try to make your applications as simple as possible. However, threads allow you to use your CPU, including its various cores, to its full potential. Figure 1 shows how processes, threads and variables are related. As you can see a thread can access two kinds of variables, local and global ones. This article will use both Python versions – you can find out which Python version is used by looking at the first line of a Python script; for Python version 2.7.x the first line of a script will be /usr/bin/python and for Python version 3.x it will be /usr/bin/python3. Please have in mind that the methodology used is more important…

Python is a great language. It has a clean and easy-tolearn syntax and you can do an awful lot in a handful of lines. It’s just not very fast, which, depending on your purposes, could be a deal-breaker. The main reason for this is that Python is interpreted: it is read line by line and converted on the fly to intermediate bytecode which gets shuffled around and eventually executed on the CPU. This takes time, but it makes life easier: there’s no need to compile your code every time you change something, and there’s no need to type your variables. The interpreter will figure out which data type everything should be, and even if you change, say, a list into an integer, it will accommodate your changes without complaint. If…

Quick tip To learn more about MongoDB you can check MongoDB: The Definitive Guide, 2nd Edition by Kristina Chodorow and MongoDB in Action, 2nd Edition by Kyle Banker, Peter Bakkum, Shaun Verch, Douglas Garrett and Tim Hawkins Let’s dive deeper into MongoDB, a document-oriented NoSQL database that has become very popular. We’ll show you how to perform various administrative tasks, with the help of a dummy table we’ll create and populate with data, and we’ll also look at how to create a Replica Set. We won’t deal with Storage Engines as the commands for database administration are the same regardless of the storage engine used. However, if you’re using MongoDB on a production server you should study WiredTiger and MMAPv1. Additionally, beginning with version 3.2 of MongoDB, WiredTiger is the…

Quick tip Perl 6 is here to stay, so the sooner you learn its new features the better it will be for you. Additionally, Perl 6 will definitely make you a better and more productive programmer so there’s no doubt that you should stick with it! Perl 6 is the latest version and it supports objectoriented programming, including generics, roles and multiple dispatch, as well as functional programming primitives, including list evaluation, junctions, autothreading and hyperoperators. One major new feature is support for multi-cores, and it also supports definable grammars which increases the pattern matching capabilities of Perl, and enables developers to perform generalised string processing. We’ll be using Rakudo, a compiler for Perl 6 code. You can install Perl 6 on an Ubuntu distro with sudo apt-get install rakudo…

Quick tip Paul Lewis has a great introductory tutorial for three.js. You’ll find it on his site at http://bit. ly/Intro2ThreeJS. For this tutorial, we’ll show you how you can use HTML5 Audio and WebGL to create an MP3 visualiser that runs in the browser. Note: this tutorial assumes an intermediate understanding of JavaScript. Three.js (MIT licence) is a Javascript library that makes easy work of doing 3D stuff in the browser; it abstracts away all the technical constructs and will enable us to work with things such as more intuitive objects, viz. cameras, lights and materials that allow us to render using either WebGL or an HTML5 canvas. WebGL is a fairly modern JavaScript API which leverages the power of the graphics processing unit (GPU) to achieve impressive physics and…

Computers aren’t actually very smart. Sure, they can do a million things in the space of a second, and help us to transmit videos of cats around the internet, but they don’t understand human languages. Ultimately, everything in a computer boils down to binary – ones and zeros – because that’s all that a CPU understands. For us programmers, this makes things a bit complicated. We can’t directly tell the CPU in English that we want to print a message on the screen, wait for a key to be pressed and so forth; we have to somehow tell the machine this information in binary. But then, imagine if your programs looked like this: That would be a nightmare, wouldn’t it? Finding mistakes would be nigh-on impossible, and if you gave…