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55 Articles

Welcome to The Python Book

Python is an incredibly versatile, expansive language that, due to its similarity to everyday language, is surprisingly easy to learn even for inexperienced programmers. It has seen a huge increase in popularity since the release and rise of the Raspberry Pi, for which Python is the officially recognised programming language. In this new edition of The Python Book, you’ll find plenty of creative projects to help you get to grips with the combination of your Raspberry Pi and Python’s powerful functionality, plus lots of tutorials that focus on Python’s effectiveness away from the tiny computer. You’ll learn all about how to code with Python from a standing start with our comprehensive masterclass, then go on to complete tutorials that will consolidate your skills and help you become fluent in the…

Welcome to The Python Book

Get started with Python

Python is a great programming language for both beginners and experts. It is designed with code readability in mind, making it an excellent choice for beginners who are still getting used to various programming concepts. The language is popular and has plenty of libraries available, allowing programmers to get a lot done with relatively little code. You can make all kinds of applications in Python: you could use the Pygame framework to write simple 2D games, you could use the GTK libraries to create a windowed application, or you could try something a little more ambitious like an app such as creating one using Python’s Bluetooth and Input libraries to capture the input from a USB keyboard and relay the input events to an Android phone. For this guide we’re…

Get started with Python

50 ESSENTIAL PYTHON COMMANDS

Python has a massive environment of extra modules that can provide functionality in hundreds of different disciplines. However, every programming language has a core set of functionality that everyone should know in order to get useful work done. Python is no different in this regard. Here, we will look at 50 commands that we consider to be essential to programming in Python. Others may pick a slightly different set, but this list contains the best of the best. We will cover all of the basic commands, from importing extra modules at the beginning of a program to returning values to the calling environment at the end. We will also be looking at some commands that are useful in learning about the current session within Python, like the current list of…

50 ESSENTIAL PYTHON COMMANDS

Basics 01 Running Python scripts On most of the UNIX systems, you can run Python scripts from the command line. 02 Running Python programs from interpreter The Python interactive interpreter makes it easy to try your first steps in programming and using all Python commands. You just issue each command at the command prompt (>>>), one by one, and the answer is immediate. Python interpreter can be started by issuing the command: In this article, all the code starting at the >>> symbol is meant to be given at the Python prompt. It is also important to remember that Python takes tabs very seriously – so if you are receiving any error that mentions tabs, correct the tab spacing. 03 Dynamic typing In Java, C++, and other statically typed languages, you…

Code a game of rock, paper, scissors

This tutorial will guide you through making a rock, paper, scissors game in Python. The code applies the lessons from the masterclass – and expands on what was included there – and doesn’t require any extra Python modules to run, like Pygame. Rock, paper, scissors is the perfect game to show off a little more about what exactly Python can do. Human input, comparisons, random selections and a whole host of loops are used in making a working version of the game. It’s also easy enough to adapt and expand as you see fit, adding rules and results, and even making a rudimentary AI if you wish. For this particular tutorial, we also recommend using IDLE. IDLE is a great Python IDE that is easily obtainable in most Linux distributions…

Code a game of rock, paper, scissors

Program a game of Hangman

One of the best ways to get to know Python is by building lots of simple projects so you can understand a bit more about the programming language. This time round, we’re looking at Hangman, a multi-round game relying on if and while loops and dealing with strings of text in multiple ways. We’ll be using some of the techniques we implemented last time as well, so we can build upon them. Hangman still doesn’t require the Pygame set of modules, but it’s a little more advanced than rock-paper-scissors. We’re playing around with a lot more variables this time. However, we’re still looking at comparisons, random selections and human input, along with splitting up a string, editing a list and even displaying rudimentary graphics. You should continue to use IDLE…

Program a game of Hangman

Play poker dice using Python

So you’ve learnt how to program rock, paper, scissors and guessed your way to victory at hangman. Now it’s time to head to Las Vegas and play our cards right. Or in this case, virtual dice, as we continue with our Python game tutorials and introduce you to some poker dice. We’re again using some of the lessons we’ve already learnt, including random number generation, list creation and modification, human input, rule setting, scoring and more. But we’ll also be adding some new skills in this tutorial. Namely, we’ll be creating and appending lists with random numbers, and using functions multiple times in one block of code to cut down on bloat. Again, we recommend using IDLE, and we’re using Python 2 to ensure compatibility with a wider variety of…

Play poker dice using Python

Create a graphical interface for Python games

The three basic games we have made in Python so far have all run in the command line or via IDLE, a Python IDE. While this allowed us to show off different ways to use Python code, we haven’t actually shown you how to present it yet. In this tutorial, we will take all three games and put them all into one neatly unified graphical interface. To this end, we’ll be making use of the small line of code we added at the bottom of each previous tutorial so we can import them as modules into our main graphical script. We’ll also modify the existing code to add some graphical elements. To do all this we’ll be using Tkinter, a default module available in Python that allows you to create…

Create a graphical interface for Python games

Bring graphics to simple Python games

We have now created a simple selector for the trio of Python games we made previously. This interface was able to launch a GUI for our rock, paper, scissors game, and run the other two in the terminal. Now, we’re going to convert the hangman and poker dice codes to work in a similar way to rock, paper, scissors. The trick with hangman comes in allowing for a different type of input, text, and the ability to have multiple rounds of the game. Tkinter allows for text entry, and we rely a lot less on ‘while’ loops to play the game in its entirety. Poker Dice needs to keep the dice analysis code, and the option to change specific dice using checkboxes. We’ll be modifying a large amount of the…

Bring graphics to simple Python games

Embed Python in C

There are times, within a C program, when you may want to execute some piece of Python code. Maybe you want to be able to run user code within your program, for example. This means you can enable users to use plug-ins to extend your program’s functionality. The way we can do this is by embedding Python within the C program. We will look at how to embed, how to run your Python code, and how to interact with the Python interpreter you’ve set up. This is functionality built into Python itself, so you don’t need to install anything extra on your Raspberry Pi, aside from the development package for Python and GCC. You will need to install them with the command: You should now have all of the tools…

Embed Python in C

Extend your Python

With the Python interpreter, you aren’t just limited to what is already available; you can extend the available functionality by defining your own Python objects, with their own methods and data, within your C code. These newly-created objects can then be called from within the Python interpreter. They are defined as static objects, with code like: The new PyObject contains the executable code for the methods to be used for your new object. You also need to create a method definition to be able to register the details with the Python interpreter. You do this by creating a PyMethodDef array: Once you have finished these two parts, you are almost ready to start using your new module code. You need to initialise it with the function: Now, you can import…

Extend your Python

System administration

System administration tasks are some of the most annoying things that you need to deal with when you have to maintain your own system. Because of this, system administrators have constantly been trying to find ways to automate these types of tasks to maximise their time. They started with basic shell scripts, and then moved on to various scripting languages. For a long time, Perl had been the language of choice for developing these types of maintenance tools. However, Python is now growing in popularity as the language to use. It has reached the point where most Linux distributions have a Python interpreter included in order to run system scripts, so you shouldn’t have any excuse for not writing your own scripts. Because you will be doing a lot system…

System administration

Running subprocesses from Python

The underlying philosophy of Unix is to build small, specialised programs that do one job extremely well. You then chain these together to build more complex behaviours. There is no reason why you shouldn’t use the same philosophy within your Python scripts. There are several utility programs available to use with very little work on your part. The older way of handling this was through using functions like “popen()” and “spawnl()” from the os module, but a better way of running other programs is by using the subprocess module instead. You can then launch a program, like ls, by using: This provides you with a long file listing for the current directory. The function “run()” was introduced in Python 3.5 and is the suggested way of handling this. If you…

Running subprocesses from Python

Web development

With the content and the bulk of the computing hosted on a server, a web application can better guarantee a consistent experience for the end user. The popular Django framework provides a very complete environment of plugins and works on the DRY principle (Don’t Repeat Yourself). Because of this, you should be able to build your web application very quickly. Since Django is built on Python, you should be able to install it with “sudo pip install Django”. Most distributions should have a package for Django, too. Depending on what you want to do with your app, you may need to install a database like MySQL or postgresql to store your application data. There are Django utilities available to automatically generate a starting point for your new project’s code: This…

Web development

Other Python frameworks

While Django is one of the most popular frameworks around for doing web development, it is by no means the only one around. There are several others available that may prove to be a better fit for particular problem domains. For example, if you are looking for a really self-contained framework, you could look at web2py. Everything you need to be able to have a complete system, from databases to web servers to a ticketing system, are included as part of the framework. It is so self-contained that it can even run from a USB drive If you need even less of a framework, there are several mini-frameworks that are available. For example, CherryPy is a purely Pythonic multi-threaded web server that you can embed within your own application. This…

Computational science

Python has become one of the key languages used in science. There is a huge number of packages available to handle almost any task that you may have and, importantly, Python knows what it isn’t good at. To deal with this, Python has been designed to easily incorporate code from C or FORTRAN. This way, you can offload any heavy computations to more efficient code. The core package of most of the scientific code available is numpy. One of the problems in Python is that the object oriented nature of the language is the source of its inefficiencies. With no strict types, Python always needs to check parameters on every operation. Numpy provides a new datatype, the array, which helps solve some of these issues. Arrays can only hold one…

Computational science

Interactive science with jupyter

For a lot of scientific problems, you need to play with your data in an interactive way. The original way you would do this was to use the Ipython web notebook. This project has since been renamed Jupyter. For those who have used a program like Mathematica or Maple, the interface should seem very familiar. Jupyter starts a server process, by default on port 8888, and then will open a web browser where you can open a worksheet. Like most other programs of this type, the entries run in chronological order, not in the order that they happen on the worksheet. This can be a bit confusing at first, but it means that if you go to edit an earlier entry, all of the following entries need to be re-executed…

Interactive science with jupyter

Robotics and electronics

Robotics is the most direct way that your code can interact with the world around you. It can read actual sensor information and move real actuators and get real work done. The first thing your robot needs is the ability to sense the world around it. The one sense that we as humans feel is most useful is sight. With web cameras being so cheap and easy to connect to hardware, vision is easy to give to your robot. The real problem is how to interpret this data. Luckily, you can use the OpenCV project to do just that. It is a vision package that can provide simple image gathering and processing, to extremely complex functions like face recognition and extraction of 3D objects. You can identify and track objects…

Robotics and electronics

ROS – Robot Operating System

While you could simply write some code that runs on a standard computer and a standard Linux distribution, this is usually not optimal when trying to handle all of the data processing that a robot needs when dealing with events in realtime. When you reach this point, you may need to look at a dedicated operating system – the Robot Operating System (ROS). ROS is designed to provide the same type of interface between running code the computer hardware it is running on, with the lowest possible overhead. One of the really powerful features of ROS is that it is designed to facilitate communication between different processes running on the computer, or potentially over multiple computers connected over some type of network. Instead of each process being a silo that…

Make extensions for Kodi with Python

Kodi (formerly XBMC) is perhaps the most important thing that has ever happened in the open source media centre space. It started its life on the original Xbox videogames console and since then it has become the de facto software for multimedia aficionados. It also has been forked into many other successful media centre applications such as Boxee and Plex. Kodi has ultimately grown into a very powerful open source application with a solid community behind it. It supports almost all major platforms, including different hardware architectures. It is available for Linux, Windows, mac OS , Android, iOS and Raspberry Pi. In these pages we will learn to build extensions for Kodi. Extensions are a way of adding features to Kodi without having to learn the core of XBMC or…

Make extensions for Kodi with Python

Scientific computing with NumPy

NumPy is the primary Python package for performing scientific computing. It has a powerful N-dimensional array object, tools for integrating C/C++ and Fortran code, linear algebra, Fourier transform, and random number capabilities, among other things. NumPy also supports broadcasting, which is a clever way for universal functions to deal in a meaningful way with inputs that do not have exactly the same form. Apart from its capabilities, the other advantage of NumPy is that it can be integrated into Python programs. In other words, you may get your data from a database, the output of another program, an external file or an HTML page and then process it using NumPy. This article will show you how to install NumPy, make calculations, plot data, read and write external files, and it…

Scientific computing with NumPy

Instant messaging with Python

Here we’ll be implementing an instant messenger in Python with a client-server architecture. This means each client connects to the server, which relays any message that one client sends to all other clients. The server will also notify the other clients when someone joins or leaves the server. The instant messenger can work anywhere a TCP socket can: on the same computer with the loopback interface, across various computers on a LAN, or even over the internet if you were to configure your router correctly. However, our messages aren’t encrypted, so we wouldn’t recommend that. Writing an instant messenger is an interesting technical problem that covers a bunch of areas that you may not have come across while programming before: • We’ll be employing sockets, which are used to transmit data…

Instant messaging with Python

Bug-sweep your code with SourceClear

The average software project today relies on dozens – sometimes hundreds – of open source libraries. Are those libraries up to date? Are there any security vulnerabilities in the versions you’re using? How would you even know? SourceClear makes it easy to answer these questions and more, automatically. You’ll get complete analysis of your open-source dependencies – security vulnerabilities, out-of-date libraries, and license reports. To analyse your project, we’ll be using the SourceClear command-line agent. By tapping into the native build and package managers that manage open-source dependencies, we’ll start by gathering information on the full dependency graph. We’ll then match up those libraries to the SourceClear Registry – the largest database in the world of open source security vulnerabilities – and help you triage the issues we might find.…

Bug-sweep your code with SourceClear

Copy: A cp to call your own

Here, we’ll be showing how to implement the cp command line utility in Python 3 – and our Python version will be called pycp. py. All operating systems offer at least one way to copy files and Linux is no exception. To understand how essential the cp command is, you should know that it is located inside /bin, which is available even if you boot your Linux machine in single user mode. Using cp The following output shows various uses of the cp utility: The first command copies the cp executable into the current directory – as you can see, the new file belongs to the current user, whereas the original file belongs to the root user. The last cp command illustrates the use of the -i option of cp.…

Copy: A cp to call your own

The strace command line utility

The strace utility enables you to see what happens behind the scenes when you execute a program or a script. Strictly speaking, strace traces the system calls and signals of an executable program and displays them on your screen. Using strace against pycp.py displays the following type of information: The aforementioned output reveals that your pycp.py script is executed as C functions and C system calls because this is the only way to communicate with the Linux kernel. Nevertheless, writing the same program in C would have required many more lines of code and many more hours of debugging.…

The strace command line utility

About UNIX file permissions

Each Linux file has permissions associated with it. Look at the following output: The first column of the previous output of the ls command shows the permissions of each file. As you can see, the permissions of each file take 10 places, which can also be viewed as bits. Apart from the first bit, which is defined by Linux and declares the type of the entry, the remaining nine places can be collected into three groups with each one having three bits. The first set explains the permissions of the user, the second set is about the permissions of the main Linux group the user belongs to, and the last part is about the permissions of the rest of the users. If you’re familiar with binary arithmetic, it’s easy to…

About UNIX file permissions

Check your mail

Since the Raspberry Pi is such a small computer, it gets used in a lot of projects where you want to monitor a source of data. One such monitor you might want to create is a mail-checker that can display your current unread emails. This issue, we’ll look at how to use Python to create your own mail-checking monitor to run on your Pi. We will focus mainly on the communications between the Pi and the mail server and not worry too much about how it might be displayed. That will be left as a further exercise. To start with, most email servers use one of two different communication protocols. The older, simpler one was called POP (Post Office Protocol), and the newer one is called IMAP (Internet Message Access…

Check your mail

What about sending emails?

In the main article, we have only looked at how to connect to an email server and how to read from it. But what if you need to be able to also send emails using code? Similar to poplib and imaplib, the Python standard library includes a module called smtplib. Again, similar to poplib and imaplib, you need to create an SMTP object for the connection, and then log in to the server. If you’re using the GMail SMTP server, you could use the code This code asks the end user for their password, but if you aren’t concerned about security, you could have it hard-coded into the code. Also, you only need to use the login() method for those servers that require it. If you are running your own…

What about sending emails?

Multitask with your Pi

The majority of programmers will learn single-threaded programming as their first computational model. The basic idea is that instructions for the computer are processed sequentially, one after the other. This works well enough in most situations, but you will reach a point where you need to start multitasking. The classical situation for writing multi-threaded applications is to have them run on a multi-processor machine of some persuasion. In these cases, you would have some heavy, compute-bound process running on each processor. Since your Raspberry Pi is not a huge 16-core desktop machine, you might be under the assumption that you can’t take advantage of using multiple threads of execution. This isn’t true, though. There are lots of problems that map naturally to the multiple thread model. You may also have…

Multitask with your Pi

Threads or processes?

What if you need to actually have truly parallel code, that has the ability to run on multiple cores? Because Python has the GIL, you need to move away from using threads and go to using separate processes to handle the different tasks. Luckily, Python includes a multiprocessing module that provides the process equivalent to the threading module. As with the threading module, you create a new process object and hand in a target function to be run. You then need to call the start() method to get it running. With threads, sharing data is trivial because memory is global and everybody can see everything. However, different processes are in different memory scopes. In order to share data, we need to explicitly set up some form of communications. You can…

Creating Pac-Man style games in Python

The code Download from linuxformat.com/archives Pac-Man is arguably one of the most famous video game characters in the world. First shooting to fame in 1980 with the release of the arcade version, Pac-Man has seen many iterations, remakes and sequels over the years, but nothing compares to the original. It’s a simple premise, really. Pac-Man is a yellow, disk-shaped, mainly feature-less character, who roams around a 2D environment collecting dots. The player has to collect all the dots in the room without being touched by any of the four enemy characters in the form of ghosts. Pinky, Blinky, Inky and Clyde are brightly coloured to stand out against the black background, being pink, red, cyan and orange, respectively. Pac-Man must avoid the ghosts and collect all the dots to progress…

Creating Pac-Man style games in Python

Multiplayer Pac-Man and more!

We might want to make some improvements to take our Pac-Man game to the next level. Consider how we might change the level layout. Perhaps when the player has picked up all the dots, we could load in a second level. We could even make the levels automatically generated, therefore creating an unlimited amount of gameplay. Some other alterations that might bring fun challenges to the game include: change where the player starts, by altering Pac-Man’s spawn location; increase or decrease the number of ghosts in the game for different levels; and make the ghosts faster or slower as the player progresses through the levels. If we really wanted to take things to the next level, we could introduce multiplayer. In the past, Pac-Man games have experimented with different forms…

Win, lose or draw?

We’ll probably need to consider adding a win and lose state to our game, so that our player experiences some closure by either winning or losing the game. We already implemented collision detection in our Move() function, so the game freezes when Pac-Man collides with a ghost. However, nothing is currently communicated to the player. Look for the following code and insert a message. You’ll see in this example we’ve printed “Game over!”: We’ll also need a way for players to win the game. For that, we’ll need to implement a win state. Perhaps code the writer turtle to print You Won! when Pac-Man has collected all the dots, using a conditional statement, checking for the score to hit 160, which is the maximum number of dots in this level.…

Win, lose or draw?

Revisit the arcade classic Pong in Python

This series of building retro games in Python has so far seen us coding a lunar landing space module (LXF262), a side-scrolling platformer (LXF263), the famous pellet-munching, ghost-chasing Pac-Man (page 104), and in this tutorial we’re going to develop our own version of Pong! To many, Pong is the original arcade game. It’s certainly the first video game to become a commercial success. Released for arcades in 1972 and for the home in 1975, Pong has gained popularity worldwide and is now permanently memorialised in the Smithsonian Institute in Washingon, DC. Developed and self-published by Atari, Pong is a 2D table tennis simulation with arguably the most simplistic game design imaginable, while managing to achieve an incredibly addictive gaming experience. What gameplay? Gameplay mechanics in Pong are quite simple. It’s…

Revisit the arcade classic Pong in Python

Taking Pong to the next level

With Pong having been around for over 40 years, we’ve seen many iterations of what is essentially quite a basic game. Once our PyGame version of the game is fully functional, perhaps we could consider what steps we might take to improve our game? On the easier end of the spectrum we could change the colour scheme from black and white to something more contemporary. When Pong was first released, black and white were the only options available. By the time the Atari came out there were 128 colours in the PAL format. Eight-bit consoles introduced 256 colours, and we’re now literally in the billions. Our game is designed in a VGA resolution, so if we were sticking to those retro/vintage aesthetics we’d only have 16 colours available to us.…

Taking Pong to the next level

Part one: Program a Space Invaders clone

When you’re learning to program in a new language or trying to master a new module, experimenting with a familiar and relatively simple project is a very useful exercise to help expand your understanding of the tools you’re using. Our Space Invaders clone is one such example that lends itself perfectly to Python and the Pygame module – it’s a simple game with almost universally understood rules and logic. While the Invaders meander their way down the screen towards you, it’s your job to pick them off while dodging their random fire. When one wave is conquered, another faster, more aggressive wave appears. We’ve tried to use many features of Pygame, which is designed to make the creation of games and interactive applications easier. We’ve extensively used the Sprite class,…

Part one: Program a Space Invaders clone

Part two: Add animation and sound to Pivaders

We had great fun creating our basic Space Invaders clone, Pivaders, for the previous tutorial. One of the key challenges with the project was keeping it to a manageable size – just 300 lines of Python. Without the use of Pygame’s strong set of features, that goal would likely have been overshot at least twofold. Pygame’s ability to group, manage and detect collisions thanks to the Sprite class really made a great difference to our project, not just in terms of length but in simplicity. If you missed the first part of the project, you can find the v0.1 code listing on GitHub via git.io/cBVTBg, while you can find version v0.2, including all the images, music and sound effects we used, over at git.io/8QsK-w. Even working within the clearly defined…

Part two: Add animation and sound to Pivaders

Create a Minecraft Minesweeper game

You may remember or have even played the classic Minesweeper PC game that originally dates back to the 60s. Over the years it has been bundled with most operating systems, appeared on mobile phones, and even featured as a mini-game variation on Super Mario Bros. This project will walk you through how to create a simple version in Minecraft: it’s Minecraft Minesweeper! You will code a program that sets out an arena of blocks and turns one of these blocks into a mine. To play the game, guide your player around the board. Each time you stand on a block you turn it to gold and collect points, but watch out for the mine as it will end the game and cover you in lava! 01 Update and install To…

Create a Minecraft Minesweeper game

Games are a great way of understanding a language: you have a goal to work towards, and each feature you add brings more fun. However, games need libraries and modules for graphics and other essential games features. While the Pygame library made it relatively easy to make games in Python, it still brings in boilerplate code that you need before you get started – barriers to you or your kids getting started in coding. Pygame Zero deals with all of this boilerplate code for you, aiming to get you coding games instantly. Pg0 (as we’ll abbreviate it) makes sensible assumptions about what you’ll need for a game – from the size of the window to importing the game library – so that you can get straight down to coding your…

Thanks to the introduction of the Web Server Gateway Interface (WSGI) in 2003, developing Python web apps for general web servers became a viable solution as opposed to restricting them to custom solutions. Python executables and installers are widely available from the official Python site at www.python.org. Mac OS X users can also benefit greatly from using Homebrew to install and manage their Python versions. Whilst OS X comes bundled with a version of Python, it has some potential drawbacks. Updating your OS may clear out any downloaded packages, and Apple’s implementation of the library differs greatly from the official release. Installing using Homebrew helps you to keep up to date and also means you get the Python package manager pip included. Once Python is installed the first package to…

Django djangoproject.com GOOD FOR: Large database-driven web apps with multiuser support and sites that need to have heavily customisable admin interfaces Django contains a lot of impressive features, all in the name of interfaces and modules. These include autowiring, admin interfaces and database migration management tools by default for all of your projects and applications. Django will help to enable rapid application development for enterprise-level projects, whilst also enabling a clear modular reuseable approach to code using subapplications. Flask flask.pocoo.org GOOD FOR: Creating full-featured RESTful APIs. Its ability to manage multiple routes and methods is very impressive Flask’s aim is to provide a set of commonly used components such as URL routing and templates. Flask will also work on controlling the request and response objects, all-in-all this means it is…

01 Install Flask Create a new directory inside of which your project will live. Open a Terminal window and navigate to be inside your new directory. Create a new virtual environment for this project, placed inside a new directory called ‘venv’, and activate it. Once inside the new virtual shell, proceed to installing Flask using the ‘pip install Flask’ command. 02 Create Index Create a new file in the root of the project location called ‘index.py’. The sample API will use a SQLite database, so we need to import that module for use in the application. We’ll also import some core components from the Flask module to handle request management and response formatting as well as some other functions. The minimum import for a Flask application is Flask itself. 03…

Python in the wild

Disqus, the popular social interaction comment service provider, has been implementing their production applications in Python for a very long time. Python’s benefit for the development team was its ability to scale effectively and cater for a large number of consumers whilst also providing an effective underlying API for internal and external use. The company are now starting to run some production apps in Go, but the majority of code still runs on Python. World-renowned image sharing service Instagram and social pin board Pinterest have also implemented Python as part of their web stack, opting for Django to assist with the functionality and ability to cater for the many thousands of content views and requests made to their services. Mozilla, Atlassian’s Bitbucket repository service, and popular satire site The Onion…

Python in the wild

Django application development

Installing Django The installation of Django is relatively easy once you have python installed. See for yourself as we build a simple app here 01 Create Virtual Environment Create a new directory for your project and navigate inside it using a new Terminal window. Create a new virtual environment for this project, opting to use the latest Python 3. Your Python 3 location may vary, so be sure to set the correct path for the binary package. 02 Activate and Install Using your Terminal window, activate the virtual environment to start the project-specific shell. VirtualEnv has a local version of the Python package manager pip installed, so it’s fairly straight forward to run the command to install Django. 03 Create Core Project The Django install contains some incredibly useful command-line…

Django application development

Hosting Python apps

Heroku heroku.com This app is perhaps one of the most well-known cloud hosting providers. Their stack server environments support a number of core web app languages including Python as standard. Their unique Toolbelt command-line features and integration with Git repositories, as well as being incredibly quick and easy to scale and improve performance, makes them an obvious choice. A free account will let you run a Python web app on one dyno instance without any cost. Python Anywhere www.pythonanywhere.com Another hosted option, and one created specifically for Python applications in general is Python Anywhere. The free basic option plan has enough weight and power behind it to get you up and running with a Python web app without having to scale, but as soon as your project gains traction, you…

Hosting Python apps

Creating dynamic templates with Flask, Jinja2 and Twitter

Python and Flask are a great combination when you’re looking to handle the Twitter OAuth process and build requests to obtain tokens. We’ve used Twitter here because of the large amount of easily digestible data available on it. However, since Twitter adheres to the standards set out by OAuth 1.0, the code we’ve used to sign and build requests can be modified to work with any third-party API using the same standard without a great deal of work. For years PHP has been a mainstay of template generation, but now with well-documented frameworks such as Flask, Sinatra and Handlebars, the ability to use powerful scripting languages greatly improves our ability to make great web services. Here, we’re going to use Python, Flask and its templating engine to display tweets. Flask…

Creating dynamic templates with Flask, Jinja2 and Twitter

Build your own blog with Django

Creating your own blog always feels like a great accomplishment. Sure, you could use the fantastic WordPress if you need a complete blog with every feature you’d ever need right now. And Tumblr exists for people who just want to write something, or post pictures of corgis in space. You don’t have full control from start to finish with a prefabricated blog, though, and neither of these is written in the fantastic Django. Django is of course based on Python, the object-orientated programming language designed to have clearly readable syntax. Due to its Python base, it’s an incredibly powerful and simple-to-use language for web development with a vast array of applications. So let’s use it to make a blog. In this first section of the process we will explore how…

Build your own blog with Django

Deliver content to your blog

In the last tutorial we began to build the most basic of blogs, and learned how to use a bit of Django in the process. We can now set up a new project, create a database and write basic code to read and write to the database. All simple stuff, but of course it’s core to building websites where Django might be called upon. Here we will give the front end of the site an overhaul, making it more of the standard you would expect from a modern blog. This will include a sidebar, pages, post pages and the ability to add and moderate comments. In the process we will learn some more of the benefits that come with using Django to develop websites. You should keep using Django 4…

Deliver content to your blog

Enhance your blog with extra features

We’ve been building our Django blog to create and display posts, allow people to make comments, and filter posts by month like a classic blog sidebar. We still have a bit of a way to go until it looks and behaves more like a classic blog, though. In this tutorial, we’re going to add in summaries, excerpts, categories and finally an RSS feed. This allows us to look at a few things – firstly we’ll get a better understanding of cross-model referencing and how that works in the admin site. We will also go through how to make changes to the database, and how Django helps when creating an SQL query. Finally, the RSS feed is part of a standard feed library in Django itself. We will learn how to…

Enhance your blog with extra features

Raspberry Pi: Build an automated news machine

News is everywhere. We are constantly bombarded with news stories via mobile devices, tablets, laptops, TVs and radios. You probably also overhear people discussing news stories. Traditionally the type of newspaper that you read was used to indicate what type of person you were – a kind of litmus test of your income, political views, social status and where your ethics and morals are aligned. For example, an article by IBT in 2013 found that 40 per cent of readers of the New Yorker were making more than $75,000 (approximately £59,000) a year. Nowadays, the news caters for every taste with variations such as gossip, detailed, statistical analysis, photographic and so many more. Then there is ‘fake news’, which is by no means a modern concept – its roots go…

Raspberry Pi: Build an automated news machine

Control a Robotic Arm with just your fingertips

This tutorial combines the Maplin Robotic Arm and Pimoroni’s Skywriter HAT to enable you to take control of the robot with just the touch of your fingertips. The arm can move through three points of articulation and ends in a clamp to give you maximum flexibility with movement. The arm also moves through 120 degrees in the wrist, 300 degrees at the elbow, 180 degrees at the base in the vertical and 270 degrees in the horizontal. It is easy to assemble and is a great beginners’ robot. In this tutorial you will first install the Python modules to enable your Raspberry Pi to interact with the USB port, and then learn how to use Python code to send commands to and receive them from the arm. Next we’ll write…

Control a Robotic Arm with just your fingertips

Hack a toy with the Raspberry Pi: Part 1

Combining an old toy and a Raspberry Pi, you can embed a selection of components to create your own augmented toy that responds to user input. For example, take a £3 R2-D2 sweet dispenser, light it up, play music and stream a live web feed to your mobile device. Part one of this two-part tutorial covers setting up four basic features: an LED for the eye, a haptic motor to simulate an electric shock, a webcam stream from a hidden camera and the Star Wars theme tune broadcast to a radio. You may choose to combine these with your own hacks or use them as standalone features in other projects. Don’t feel limited to just using a Star Wars toy either – we used the R2D2 figure because it was…

Hack a toy with the Raspberry Pi: Part 1

Hack a toy with the Raspberry Pi: Part 2

In part one of this ‘hack a toy’ tutorial you created four hacks that were originally used to augment a £3 R2D2 sweet dispenser making it light up, vibrate, play music and stream a live web feed to a mobile device. You may have been working on your own features to use and customise your toy. Part two of this tutorial begins by showing two different ways to set up and use a button to trigger your hacks. One method is to add and code your own button, the second method is to utilise the toy’s own built-in button. The next part walks you through how to wire up, code and test each of the individual features before combining them into a single program which will bring your toy to…

Hack a toy with the Raspberry Pi: Part 2

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HOW TO USE FileSil

To access FileSilo, please visit www.filesilo.co.uk/bks-1387 01 Click on the link above to access the content at any time and download it to your desktop. 02 You are now free to explore the wealth of content available on FileSilo, from great video tutorials and exclusive online guides to superb downloadable resources. For this bookazine you’ll find tutorial files to help you code with Python. 03 You can access FileSilo on any desktop, tablet or smartphone device using any popular browser (such as Safari, Firefox or Google Chrome). However, we recommend that you use a desktop to download content, as you may not be able to download files to your phone or tablet. 04 If you have any problems with accessing content on FileSilo take a look at the FAQs online…

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