Indholdsfortegnelse for The Python Coding Manual i The Python Coding Manual

Coding can be one of those experiences that sounds fantastic, but to get going with it, is often confusing. After all, there’s a plethora of languages to choose from, numerous apps that will enable you to code in a specific, or range, of languages and an equally huge amount of third-party software to consider. Then you access the Internet and discover that there are countless coding tutorials available, for the language in which you’ve decided you want to program, alongside even more examples of code. It’s all a little too much at times. The trick is to slow down and, to begin with, not look too deeply into coding. Like all good projects, you need a solid foundation on which to build your skill and to have all the necessary…

INSTALLING PYTHON 3.X Microsoft Windows doesn’t come with Python preinstalled as standard, so you’re going to have to install it yourself manually. Thankfully, it’s an easy process to follow. STEP 1 Start by opening your web browser to www.python.org/downloads/. Look for the button detailing the download link for Python 3.x. Python is regularly updated, changing the last digit for each bug fix and update. Therefore, don’t worry if you see Python 3.7.3, or more, as long as it’s Python 3, the code in this book will work fine. STEP 2 Click the download button for version 3.x, and save the file to your Downloads folder. When the file is downloaded, double-click the executable and the Python installation wizard will launch. From here you have two choices: Install Now and Customise…

WHAT IS PROGRAMMING? It helps to understand what a programming language is before you try to learn one, and Python is no different. Let’s take a look at how Python came about and how it relates to other languages. PYTHON A programming language is a list of instructions that a computer follows. These instructions can be as simple as displaying your name or playing a music file, or as complex as building a whole virtual world. Python is a programming language conceived in the late 1980s by Guido van Rossum at Centrum Wiskunde & Informatica (CWI) in the Netherlands as a successor to the ABC language. Guido van Rossum, the father of Python. PROGRAMMING RECIPES Programs are like recipes for computers. A recipe to bake a cake could go like…

PLAYING WITH PYTHON As with most languages, computer or human, it’s all about remembering and applying the right words to the right situation. You’re not born knowing these words, so you need to learn them. STEP 1 If you’ve closed Python 3 IDLE, re-open it as you did in the previous page. In the Shell, enter the familiar following: STEP 2 As predicted, the word Hello appears in the Shell as blue text indicating output from a string. It’s fairly straightforward, and doesn’t require too much explanation. Now try: STEP 3 You’ll notice that instead of the number 4, the output is the 2+2 you asked to be printed to the screen. The quotation marks are defining what’s being outputted to the IDLE Shell, to print the total of 2+2…

IT’S ALL MATHS, MAN You can get some really impressive results from the mathematical powers of Python, as maths is the driving force behind the code with most, if not all, programming languages. STEP 1 Open up the GUI version of Python 3, as mentioned you can use either the Shell or the Editor. For the time being, we’re going to use the Shell. If you’ve opted to use a third-party text editor, note that you need to get to the IDLE Shell for this part of the tutorial. STEP 2 In the Shell enter the following: As you can see, Python can handle some quite large numbers. STEP 3 You can use all the customary Mathematical operations: divide, multiply, brackets and so on. Practise with a few, for example:…

USER FRIENDLY The type of input you want from the user will depend greatly on the type of program you’re coding. A game, for example, may ask for a character’s name, whereas a database can ask for personal details. STEP 1 If it’s not already, open the Python 3 IDLE Shell, and start a New File in the Editor. Let’s begin with something really simple, enter: STEP 2 Save and execute the code, and, as you no doubt suspected, in the IDLE Shell the program will ask for your first name, storing it as the variable firstname, followed by your surname; also stored in its own variable (surname). STEP 3 Now that we have the user’s name stored in a couple of variables, we can call them up whenever we…

MASTERING MODULES Think of modules as an extension that’s imported into your Python code to enhance and extend its capabilities. There are countless modules available, and as we’ve seen, you can even make your own. STEP 1 Although good, the built-in functions within Python are limited. The use of modules, however, allows us to make more sophisticated programs. As you are aware, modules are Python scripts that are imported, such as import math. STEP 2 Some modules, especially on the Raspberry Pi, are included by default; the Math module is a prime example. Sadly, other modules aren’t always available. A good example on non-Pi platforms is the Pygame module, which contains many functions to help create games. Try: import pygame. STEP 3 The result is an error in the IDLE…

Data is everything. It’s more valuable than gold or oil. With data, governments can change the world, politicians can rise or fall, and companies, large or small, can impact our future in ways we wouldn’t have imagined just a few years ago. Data is power, and learning how to manipulate and control it are essential aspects of any coding language. Here we’ll take a look at how you can use date and time functions, write to files in your system, and even create graphical user interfaces that will take your coding skills to new levels and open more doors for you.…

KEY PAIRS A dictionary is like a list, but instead each data item comes as a pair, these are known as Key and Value. The Key part must be unique and can either be a number or string, but the Value can be any data item you like. STEP 1 Let’s say you want to create a phonebook in Python. You would create the dictionary name, and contain the data in curly brackets, separating the key and value by a colon Key:Value. For example: STEP 2 As with most lists, tuples, and so on, strings need to be enclosed in quotes (single or double), while integers can be left open. Remember that the value can be either a string, or an integer, you just need to enclose the relevant one…

TIME LORDS The Time module contains functions that help you retrieve the current system time, read the date from strings, format the time and date, and much more. STEP 1 First you need to import the Time module. It’s one that’s built-in to Python 3, so you shouldn’t need to drop into a command prompt and pip install it. Once it’s imported, we can call the current time and date with a simple command: STEP 2 The time function is split into nine tuples, these are divided up into indexed items, as with any other tuple, and shown in the screen shot below. STEP 3 You can see the structure of how time is presented by entering: time.local.time() The output is displayed as such: ‘time.struct_time(tm_ year=2019, tm_mon=9, tm_mday=7, tm_hour=9, tm_min=6,…

EXCEPTIONAL OBJECTS Rather than stop the flow of your code, Python includes exception objects, which handle unexpected errors in the code. We can combat errors by creating conditions where exceptions may occur. STEP 1 You can create an exception error by simply trying to divide a number by zero. This will report back with the ZeroDivisionError: Division by zero message, as seen in the screenshot. The ZeroDivisionError part is the exception class, of which there are many. STEP 2 Most exceptions are raised automatically when Python comes across something that’s inherently wrong with the code. However, we can create our own exceptions that are designed to contain the potential error and react to it, as opposed to letting the code fail. STEP 3 We can use the functions raise exception…

WORKING WITH DATES The Calendar module is built into Python 3. However, if, it’s not installed, you can add it using pip install calendar, as a Windows administrator, or sudo pip install calendar for Linux and macOS. STEP 1 Launch Python 3 and enter: import calendar to call up the module and its inherent functions. Once it’s loaded into memory, start by entering: STEP 2 You can see that the days of September 2019 are displayed in a wall calendar fashion. Naturally you can change the 2019, 9 part of the second line, to any year and month you want, a birthday for example (1973, 6). The first line configures TextCalendar to start its weeks on a Sunday; you can opt for Monday if you prefer. STEP 3 There are…

RANDOM NUMBERS There are numerous functions within the Random module, which, when applied, can create some interesting and very useful Python programs STEP 1 As with other modules, you’ll need to import random before you can use any of the functions we’re going to look at in this tutorial. Let’s begin by simply printing a random number from 1 to 5: STEP 2 In our example the number three was returned. However, enter the print function a few more times and it will display different integer values from the set of numbers given, zero to five. The overall effect, although pseudo-random, is adequate for the average programmer to utilise in their code. STEP 3 For a bigger set of numbers, including floating point values, we can extend the range by…

LIGHTS, CAMERA, ACTION The Tkinter module is an ideal starting point to learning animation within Python. Naturally, there are better custom modules out there, but Tkinter does the job well enough to get a grasp on what’s needed. STEP 1 Let’s make a bouncing ball animation. First, we will need to create both a canvas (window) and the ball to animate: STEP 2 Save and Run the code. A blank window will appear, with a red ball sitting in the upper left corner of the window. While great, it’s not very animated. Let’s add the following code: STEP 3 Insert the new code between the ball1 = canvas.create_oval(5,5,60,60, fill=’red’) line, and the gui.mainloop() line. Save it and Run. You will now see the ball move from the top left corner…

Linux is a surprisingly powerful, fast, secure, and capable operating system. It’s used as the OS of choice for the Raspberry Pi, in the form of Raspbian OS, as well as in some of the most unlikely places. Despite only enjoying 1.96% (according to netmarketshare.com) of the total desktop operating system market, Linux has a dedicated following of enthusiasts, users, and contributors. It was created in 1991 by then University of Helsinki student, Linus Torvalds, who had become frustrated with the limitations and licensing of the popular educational system in use called Minix; a miniature version of the UNIX operating system. UNIX itself was released in the early ‘70s, as a multi-tasking, modular-designed operating system, originally developed for programmers who needed a stable platform on which to code. However, its…

LOOKING AT FILES Operating systems are built on files and folders, or directories if you prefer. While you’re used to viewing your own files, most operating systems keep other files out of sight. In Raspbian, you have access to every file in the system. STEP 1 We’ve already looked at “ls”, which lists the files in the working directory, but you are more likely to use a command like “ls –l”. The bit after the command (the ‘-lah’) is known as the argument. This is an option that modifies the behaviour of the command. STEP 2 The “-l” argument lists files and directories in long format. Each file and directory is now on a single line, and before each file is a lot of text. First you’ll see lots of…

USING THE MOVE COMMAND In Linux, renaming a file is simply moving it from one name to another and copying a file is moving it without deleting the original. Don’t panic, it’s quite easy to master. STEP 1 Before we can move anything around, we need to have a few test items in our home directory. Enter: touch testfile and mkdir testdir to create a test file and test directory in your home directory. Enter: ls to check that they are both present. STEP 2 Files and directories are moved using the mv command. This is different to the commands we’ve looked at so far because it has two arguments (remember Linux command line is command, option, argument). The first argument is the source (the file or directory to be…

WHAT IS A USER? An important part of using Linux is the concept of users and understanding which user you are and which group you belong to. Like all modern computers, you can have multiple user accounts with each having different levels of access. STEP 1 The first thing you need to do is get a concept of which user you are. Enter: whoami into the command line and press return. It should say “pi” (unless you set up your account name differently during setup). The “whoami” command might seem a bit simplistic, but it comes in very handy sometimes. STEP 2 When you are working in Linux, from time to time a ‘Permission denied’ error will occur, typically when you try to create, edit or execute (run) a file…

PROGRAMS AND PROCESSES Linux has a trick up its sleeve when it comes to being able to manage programs and processes. When Windows closes a program, the allocated memory often isn’t freed up again. However, Linux is far more streamlined. STEP 1 As you get into Linux you’ll start to hear more about processes and another thing called the “kernel”. The kernel sits beneath the software and hardware. It passes instructions to the hardware running processes, which takes up memory, and when the process is finished it closes it and reclaims the memory. STEP 2 You’re probably used to thinking in terms of programs and most OS’s tend to keep processes out of sight. In Linux on the other hand, you’re right in at the deep end. A process is…

MORE FUN, YAY Since the Terminal session is already open, and your keyboard digits are nicely warmed up, here are another two pages of Terminal nonsense. STEP 1 Remember the old ZX Spectrum days of computing, when you could type in 10 print “Hello”, 20 goto 10 and Hello would list down the screen? Well, in Raspbian you can do the same. Simply enter: yes followed by some text, i.e. yes Raspberry Pi is ace. It keeps going until you press Ctrl+C. STEP 2 The Matrix was one of the most visually copied films ever released and there’s even a version of the Matrix code available for Linux. Install it with: sudo apt-get install cmatrix. When it’s done enter: cmatrix and follow the white rabbit, Neo. Unlike the real Matrix…

A adduser Add a new user arch Print machine architecture awk Find and replace text within file(s) B bc An arbitrary precision calculator language C cat Concatenate files and print on the standard output chdir Change working directory chgrp Change the group ownership of files chroot Change root directory cksum Print CRC checksum and byte counts cmp Compare two files comm Compare two sorted files line by line cp Copy one or more files to another location crontab Schedule a command to run at a later time csplit Split a file into context-determined pieces cut Divide a file into several parts D date Display or change the date & time dc Desk calculator dd Data Dump, convert and copy a file diff Display the differences between two files dirname Convert…

NUMBERGUESS.PY Copy the code and see if you can beat the computer within five guesses. It’s an interesting bit of code that can be quite handy when your implementing a combination of the Random module alongside a while loop. 1 Although this is a reasonably easy to follow program, there are some elements to the code that are worth pointing out. To begin with, you need to import the Random module, as you’re using random numbers within the code. 2 This section of the code creates the variables for the number of guesses used, along with the name of the player, and also sets up the random number between 1 and 30. If you want a wider range of random number selection, then increase the number=random.randint(1, 30) end value of…

RNDPASSWORD.PY Copy the code and run it; each time you’ll get a random string of characters that can easily be used as a secure password which will be incredibly difficult for a password cracker to hack. Secure Passwords There’s plenty you can do to modify this code and improve it further. For one, you can increase the number of characters the generated password displays and perhaps you can include special characters too, such as signs and symbols. Then, you can output the chosen password to a file, then securely compress it using the previous random number generator as a file password and send it to a user for their new password. An interesting aspect to this code is the ability to introduce a loop and print any number of random…

GOOGLESEARCH.PY You will need to pip install the Urllib module, unless it’s already installed. It also uses Zenity, which is a Linux-based (GNOME) tool for creating dialog boxes. Searching For More Here we’ve used the Zenity command to create the dialog box, which as we mentioned is only available to Linux machines (such as Ubuntu, Raspberry Pi, Linux Mint and so on). If you want to execute it in Windows you have a couple of possibilities: you can find a Windows version of Zenity and pass the user’s query through it; or you can create a Tkinter dialog box to pass the information. You can see that this particular code uses the Chromium browser which comes preinstalled on the Raspberry Pi, and some versions of Linux. To use your favourite…

MOUSETURTLE.PY The first piece of code presents the standard Turtle window. Press Space and then click anywhere on the screen for the Turtle to draw to the mouse pointer. The second allows you to click the Turtle and drag it around the screen; but be warned, it can crash Python. 1st Code Example: 2nd Code Example: Ninja TurtleMouse This code utilises some interesting skills. Obviously it will stretch your Python Turtle skills to come up with any improvements, which is great, but it could make for a nice piece of code to insert into something a young child will use. Therefore it can be a fantastic project for a younger person to get their teeth into; or perhaps even as part of a game where the main character is tasked…

DIGCLOCK.PY This is a surprisingly handy little script and one that we’ve used in the past instead of relying on a watch or even the clock in the system tray of the operating system. Tick Tock This is a piece of code we’ve used many times in the past to keep track of time while working on multiple monitors and with just a quick glance to where we’ve placed it on the screen. The Tkinter box can be moved around without affecting the time, maximised or closed by the user at will. We haven’t given the Tkinter clock window a title, so you can add to that easily enough by snipping the code from other examples in this book. Another area of improvement is to include this code when Windows…

MUSIC.PY The code utilises both the Time and Winsound modules, defining the tone and pitch and inserting small pauses of .5 of a second. 1 The start of the code imports the Winsound and Tie modules; remember, this is a Windows-only Python script. The variable t is setting the duration, while p equals .5, which you can use for the time.sleep function. 2 These variables set the frequencies, with the corresponding numbers, which can be used in the next section of the code. 3 Winsound.beep requires a frequency and duration within the brackets. The frequencies come from the large set of variables called in the second section of the code and the duration is through the t variable set at the start of the code. There’s a half-second, using the…

LOAD”” Back in the 80s, in the 8-bit home computing era, loading screens were often used to display the cover of a game as it loaded from tape. The image would load itself in, usually one-line-at-a-time, then proceed to colour itself in while the loading raster bars danced around in the borders of the screen. Loading screens were a part of the package, and the buy-in for the whole game as an experience. Some loading screens featured animations, or a countdown for time remaining as the game loads, while others even went so far as to include some kind of playable game. The point being: a loading screen is not just an artistic part of computing history, but an introduction to the program that’s about to be run. While these…

01000011 01101111 01100100 01100101 Essentially all forms of coding are made up of ones and zeros, on or off states. This works for a modern computer and even the oldest known computational device. ~87 BC It’s difficult to pinpoint an exact start of when humans began to ‘program’ a device. However, it’s widely accepted that the Antikythera Mechanism is possibly the first ‘coded’ artefact. It’s dated to about 87 BC and is an ancient Greek analogue computer and orrery used to predict astronomical positions. ~850 AD The Banū Mūsā brothers, three Persian scholars who worked in the House of Wisdom in Baghdad, published the Book of Ingenious Devices in around 850 AD. Among the inventions listed was a mechanical musical instrument: a hydro-powered organ that played interchangeable cylinders automatically. 1800…

Sounds good, but what exactly is a Virtual Machine and how does it work? The official definition of a virtual machine is ‘an efficient, isolated duplicate of a real computer machine’. This basically means that a virtual machine is an emulated computer system that can operate in exactly the same way as a physical machine, but within the confines of a dedicated virtual machine operator, or Hypervisor. The Hypervisor itself, is an app that will allow you to install a separate operating system, creating a virtual computer system within itself complete with access to the Internet, your home network and so on. The Hypervisor will take resources from the host system - your physical computer, to create the virtual computer. This means that part of your physical computer’s: memory, CPU,…

Python’s ability to create highly readable code within a small set of instructions has a considerable impact on our modern digital world. From the ideal, first programmers’ choice to it’s ability to create interactive stories and games; from scientific applications to artificial Intelligence and web-based applications, the only limit to Python is the imagination of the person coding in it. It’s Python’s malleable design that makes it an ideal language for many different situations and roles. Even certain aspects of the coding world, that require more efficient code, still use Python. For example, NASA utilises Python both as a stand-alone language and as a bridge between other programming languages. This way, NASA scientists and engineers are able to get to the data they need without having to cross multiple language…

PYTHON PENGUIN Linux is such a versatile operating system that it’s often difficult to nail down just one-way of doing something. Different distributions go about installing software in different ways, so for this particular tutorial we will stick to Linux Mint. STEP 1 First you need to ascertain which version of Python is currently installed in your Linux system. To begin with, drop into a Terminal session from your distro’s menu, or hit the Ctrl+Alt+T keys. STEP 2 Next, enter: python --version into the Terminal screen. You should have the output relating to version 2.x of Python in the display. Most Linux distro come with both Python 2 and 3 by default, as there’s plenty of code out there still available for Python 2. Now enter: python3 --version. STEP 3…

Now that you have the latest version of Python installed, you can begin to get programming. These are your first steps in the wider world of Python and we’re here to help you write your first piece of code, save it, and run it in the Python IDLE Shell. We cover variables, numbers and expressions, user input, conditions and loops, and the types of errors you will undoubtedly come across in your time with Python. Let’s start and see how to get coding.…

EDITING CODE You will eventually reach a point where you have to move on from inputting single lines of code into the Shell. Instead, the IDLE Editor will allow you to save and execute your Python code. STEP 1 First, open the Python IDLE Shell. When it’s up, click on File > New File, this will open a new window with Untitled as its name. This is the Python IDLE Editor, and within it, you can enter the code you need to create your future programs. STEP 2 The IDLE Editor is, for all intents and purposes, a simple text editor with Python features, colour coding and so on. You enter code as you would within the Shell, so taking an example from the previous tutorial, enter: STEP 3 As…

#COMMENTS! A method used by most programmers for keeping their code readable, is by commenting on certain sections. For example, if a variable is used, the programmer comments on what it’s supposed to do. It’s just good practise. STEP 1 We’ll start by creating a new instance of the IDLE Editor (File > New File), and then create a simple variable and print command: Save the file, and execute the code. STEP 2 Running the code will return the line: The value of A is, 10 into the IDLE Shell window – which is what we expected. Now let’s add some of the types of comments you’d normally see within code: STEP 3 Re-save the code and execute it. You’ll see that the output in the IDLE Shell is still…

FUNKY FUNCTIONS A function is a command that you enter into Python in order to do something. It’s a little piece of self-contained code that takes data, works on it, and then returns the result. STEP 1 It’s not only data that a function works on. Functions can do all manner of useful things in Python, such as sort data, change items from one format to another, and check the length or type of items. Basically, a function is a short word followed by brackets. For example, len(), list(), or type(). STEP 2 A function takes data, usually a variable, works on it depending on what the function is programmed to do, and returns the end value. The data being worked on goes inside the brackets, so if you wanted…

DEBUGGING Errors in code are called bugs, they’re perfectly normal and can often be easily rectified with a little patience. The import thing is to keep looking, experimenting, and testing. Eventually your code will be bug free. STEP 1 Code isn’t as fluid as the written word, no matter how good the programming language is. Python is certainly easier than most languages, but even it is prone to some annoying bugs. The most common are typos by the user, and while easy to find in simple dozen-line code, imagine having to debug multi-thousand line code. STEP 2 As we’ve mentioned, the most common of errors is the typo, often at the command level, mistyping the print command for example. However, they also occur when you’ve got numerous variables, all of…

WORKING WITH LISTS Lists are extremely handy in Python. A list can be strings, integers, and also variables. You can even include functions in lists, and lists within lists. STEP 1 A list is a sequence of data values called items. You create the name of your list followed by an equal sign, then square brackets and the items separated by commas; note that strings use quotes: STEP 2 Once you’ve defined your list, you can call each by referencing its name followed by a number. Lists start the first item entry as 0, followed by 1, 2, 3, and so on. For example: numbers To call up the entire contents of the list. numbers[3] To call the item third from zero in the list (21 in this case). STEP…

STRING THEORIES We’ve already looked at some list functions, using .insert, .remove, and .pop, but there are also functions that can be applied to strings. STEP 1 The main tool in the string function arsenal is .split(). With it, you’re able to split apart a string of data, based on the argument within the brackets. For example, here’s a string with three items, each separated by a space: STEP 2 Now let’s turn the string into a list, and split the content accordingly: And enter the name of the new list, names, to see the three items. STEP 3 Note that the text.split part contains the brackets, quotes, then a space followed by closing quotes and brackets. The space is the separator, indicating that each list item entry is separated…

OPEN, READ AND WRITE In Python, you create a file object, similar to creating a variable, only you pass in the file using the open() function. Files are usually categorised as text or binary. STEP 1 Start by entering some text into your system’s text editor. The text editor is preferable to a word processor, as word processors include background formatting and other elements. In our example, we have the poem The Cimmerian, by Robert E Howard, and we’ve saved the file as poem.txt. STEP 2 You use the open() function to pass the file into a variable as an object. You can name the file object anything you like, but you will need to tell Python the name and location of the text file you’re opening: poem=open(“C:\\Users\\david\\Documents\\poem.txt”) The reason…

GOING GRAPHICAL You can draw simple graphics, lines, squares and so on, or you can use one of the many Python modules available to bring out some spectacular effects. STEP 1 One of the best graphical modules to begin learning Python graphics is Turtle. The Turtle module is, as the name suggests, based on the turtle robots used in many schools that can be programmed to draw something on a large piece of paper on the floor. The Turtle module can be imported with: import turtle. STEP 2 Let’s begin by drawing a simple circle. Start a New File, then enter the following code: As usual press F5 to save the code and execute it. This will open up a new window and the ‘Turtle’ will draw a circle. STEP…

INTO THE SYSTEM One of the primary features of the OS module is the ability to list, move, create, delete and otherwise interact with files stored on the system; making it the perfect module for backup code. STEP 1 We can start the OS module with some simple functions to see how it interacts with the operating system environment that Python is running on. If you’re using Linux, or the Raspberry Pi, try this: STEP 2 The returned result, from printing the variable home, is the current user’s home folder on the system. In Step 1 that’s /home/pi, it will be different depending on the user name you login as, and the operating system you use. For example, Windows 10 would output: C:\Users\david\AppData\ Local\Programs\Python\Python37-32. STEP 3 The Windows output is…

GETTING GUI Tkinter is easy to use, but there’s a lot more you can do with it. Let’s start by seeing how it works, and then getting some code into it. STEP 1 Tkinter is usually built into Python 3, however if it’s available when you enter: import tkinter, then you’ll need to pip install tkinter from the command prompt. We can start to import modules differently than before, to save on typing, by importing all their contents: STEP 2 Although it’s not recommended to import everything from a module using the asterisk, normally it won’t do any harm. Let’s begin by creating a basic GUI window, enter: wind=Tk() This creates a small, basic window. At this point, there’s not much else to do but click the X in the…

BUILDING MODULES Modules are Python files, containing code, that you save using a .py extension. These are then imported into Python using the now familiar import command. STEP 1 Let’s start by creating a set of basic Mathematics functions. Multiply a number by two or three, and square or raise a number to an exponent (power). Create a New File in the IDLE and enter: STEP 2 Under the above code, enter functions to call the code: Save the program as basic_math.py and execute it to get the results. STEP 3 Now we’re going to take the function definitions out of the program and into a separate file. Highlight the function definitions and choose Edit > Cut. Choose File > New File and use Edit > Paste in the new…

FREE AND OPEN Linux is a fantastic fit for those who want something different. The efficiency of the system, the availability of applications, and its stability are just a few reasons why it’s a great Python coding resource. The first thing we need to address is that there is no such operating system called Linux. Linux is, in fact, the operating system kernel, the core component of an OS. When talking about Linux, what we, and others, are referring to is one of the many distributions, or distros, that use the Linux kernel. No doubt you’ve heard of at least one of the current popular distros: Ubuntu, Linux Mint, Fedora, openSUSE, Debian, Raspbian… the list goes on. Each one of these distros offers the user something a little different. While…

CREATING FILES Once you learn to recognise the files and directories that make up Raspbian OS, it’s time to discover how to make your own. Knowing how to make, edit and delete files and directories is essential if you want to make your own projects. STEP 1 We’re going to create a file using a command called Touch. Touch is an interesting command that reaches out to a file, or directory, and updates it (this changes the system time as if you’d just opened the file). You can see Touch in access using “ls –l” and checking the time next to a directory (such as Scratch). STEP 2 Now enter: touch Scratch and ls –l again and notice that the time has changed. It now matches the current time. You…

HEY, MAN! The man pages are one of the best features of Linux, and as a built-in tool it’s invaluable for both beginner and senior level Linux administrators. Let’s see how it works STEP 1 Linux has a built-in manual, known as man for short. Using the man command you can obtain information on all the Linux commands we’ve talked about. Simply enter: man and the name of the command you want to learn more about. Start by entering: man ls in the command line. STEP 2 The man pages are a bit more detailed than you might be used to. First you have a name, which tells you what the command is called; in this case “list directory contents” and then the synopsis shows you how it works. In…

OWNER AND PRIVILEGE Each user account in Linux is an owner of a section of the filesystem: their Home area. Within this area, they do what they like (within reason), as they have owner privileges. Elsewhere though, they usually just have read-only privileges. STEP 1 If you followed the previous tutorial you should now have two accounts on your Raspberry Pi. One called “pi” and the other with a name (Lucy in our case). An essential aspect of Linux is the idea of file and directory ownership; who owns, and has access, to what. You need a test file so enter: touch testfile. STEP 2 Now enter: ls –l and let’s have a good look at the default permissions file. Our testfile.txt files starts with the text “-rw-r--r—“. Start with…

IN, OUT, LINUX ALL ABOUT Everything on a computer is about input and output. You input things into the computer (press keys, move the mouse) and it makes calculations and outputs content (changes the display, makes a noise, for example). STEP 1 When you enter commands into Linux (in the command line), you are using standard input and output. This is so obvious that most people don’t even think about it. You enter commands using the keyboard (that’s input) and it responds to the screen (output). This is the regular way of doing it, which is why it’s “standard input and output” (often called “stdin” and “stdout” for short). STEP 2 As far as the computer is concerned, input and output can be to and from a whole range of…

TAKING COMMAND There are countless Linux tips, secrets, hacks and tricks out there. Some are very old, originating from Linux’s Unix heritage, while others are recent additions to Linux lore. Here are our ten favourite tips and tricks. EASTER EGGS Emacs text editor, is a great piece of software but did you know it also contains a hidden Easter Egg? With Emacs installed (sudo apt-get install emacs24), drop to a Terminal session and enter: emacs -batch -l dunnet Dunnet is a text adventure written by Ron Schnell in 1982, and hidden in Emacs since 1994. MOON BUGGY Based on the classic 1982 arcade game, Moon Patrol, Moon Buggy appeared on home computers in 1985 amid much praise. It’s a cracking Atari game available in the Linux Terminal by entering: sudo…

We’ve included a unique Python code repository for you to freely use in your own programs. There’s everything you can think of in here to help you create a superb piece of programming. We’ve got code that covers number guessing games, random number generators, Google search code, game code, animation code, graphics code, text adventure code, and even code that plays music stored on your computer. This is an excellent resource that you won’t find in any other Python book. So use it, take it apart, adapt it to your own programs, and see what you can create. SHARE YOUR CODE! The code listed within this section can be downloaded as a Python file, so you don’t have to type it out. Simply visit www.bdmpublications.com/code-portal, sign up for access to…

POLYGONCIRCLES.PY There’s lots of mathematics used here along with some intricate coordinate manipulation with the Turtle module. Enter the code and execute it to see how it turns out. Graphical Enhancements There are several ways in which you can improve this code to make it more interesting. You can insert colours, perhaps a different colour for every line. You can display a message inside the circle and have the Turtle draw around it. Let your imagination run wild on this one. Turtle’s graphics can take a while to map out and draw, depending on how big and how intricate an image it is you’re designing. Whilst the effect can be quite stunning, it is limited by the amount of time it takes to display an image. Therefore it’s worth seeing…

KEYBDRAW.PY There are two modules in this script: Turtle and Tkinter. The Turtle module is the main display, where the user controls the drawing, whereas Tkinter simply displays the user controls. Artwork Just as with all code, there’s always room for improvement somewhere. Here you could change the colours or ask the user which colour they want to start with and then include a key in the controls to change the pen colour whilst drawing. There’s also room to increase or decrease the speed of the pen, again that could be a user-defined speed. You can also expand the controls thoroughly to include a lot more detail and options. 1 An initial set of comments to display the controls, which can also be outputted as a separate tkinter window if…

TXT2BIN.PY Naturally we’re using the format function to convert the user’s entered text string into its binary equivalent. If you want to check its accuracy, you can plug the binary into an online convertor. 1000010 1101001 1101110 1100001 1110010 1111001 The text to binary convertor does offer some room for improvement and enhancement. There are many uses: it could be utilised in a password or secret word script, as part of an adventure game or just a novel way to display someone’s name. With regards to improvements, you could display the binary conversion in a Pygame window, using the animated text options from page 100. You could also ask the user if they wanted to have another go, or even ask if they wanted the binary output to be saved…

ALARMCLOCK.PY This code is designed for use in the command prompt, be that Windows, Linux or macOS. There are some instructions on how to use it in the main print section but essentially it’s: python3 AlarmClock.py 10 (to go off in ten minutes). Wakey Wakey There’s some good use of try and except blocks here, alongside some other useful loops that can help you get a firmer understanding of how they work in Python. The code itself can be used in a variety of ways: in a game where something happens after a set amount of time or simply as a handy desktop alarm clock for your tea break. Linux users, try making the alarm clock code into an alias, so you can run a simple command to execute it.…

TICKER.PY We’re using Tkinter here along with the Time module to determine the speed the text is displayed across the window. Ticker Time The obvious improvements to the Ticker code lie in the speed of the text and what the text will display. Otherwise you can change the background colour of the ticker window, the font and the font colour, along with the geometry of the Tkinter window if you want to. Yet another interesting element that could be introduced is one of the many text to Speech modules available for Python 3. You could pip install one, import it, then as the ticker displays the text, the text to speech function will read out the variable at the same time, since the entire text is stored in the variable…

HANGMAN.PY We’ve made a Hangman game board (the gallows) out of characters that can be displayed in the IDLE Shell, along with a huge bank of words to randomly choose from. QUIT() Since this is the last example in our Python code repository, we thought we’d go out with a bang and feature the hangman gallows being drawn with each incorrect guess of the word. Don’t worry if it looks misaligned in the text here, this is merely due to the differences between using the Python IDLE editor and pasting the code into a word processor (which formats things differently). There’s plenty you can do to improve, enhance and expand on what we’ve presented here. You can include a routine that returns an error if the user enters a number…

THE FINAL COUNTDOWN Let’s begin with some example code that will display a large countdown from ten, then clear the screen and display a message. The code itself is quite simple, but lengthy. You will need to start by importing the OS and Time modules, then start creating functions that display the numbers: and so on to 10. It’ll take some time, but it’s worth it in the end. Of course, you can always take a different approach and design the numbers yourself. The next step of the process is to initialise the code settings and start the countdown: And finally, we can add a display for the message: The code in its entirety can be viewed from within our Code Repository: bdmpublications.com/ code-portal, where you’re free to copy it…

ASCII ANIMATION Let’s assume you wanted to create an animated ASCII Happy Birthday Python script, with the words Happy and Birthday alternating in appearance. Here’s how it’s done. STEP 1 First we need to create some ASCII-like text, head over to http://patorjk.com/software/taag. This is an online Text to ASCII generator, created by Patrick Gillespie. Start by entering Happy into the text box, the result will be displayed in the main window. You can change the font with the drop-down menu, to the side of the text box; we’ve opted for Big. STEP 2 Now create a folder in your Python code directory on your computer (call it Test, for now), and open either Notepad for a Windows 10 computer, or, if you’re using Linux, then the currently installed text editor.…

DEF BEGINNER(MISTAKES=10) Here are ten common Python programming mistakes most beginners find themselves making. Being able to identify these mistakes will save you headaches in the future. VERSIONS To add to the confusion that most beginners already face when coming into programming, Python has two live versions of its language available to download and use. There is Python version 2.7.x and Python 3.6.x. The 3.6.x version is the most recent, and the one we’d recommend starting. But, version 2.7.x code doesn’t always work with 3.6.x code and vice versa. THE INTERNET Every programmer has and does at some point go on the Internet and copy some code to insert into their own routines. There’s nothing wrong with using others’ code, but you need to know how the code works and…

SQL SQL stands for Structured Query Language. SQL is a standard language for accessing and manipulating databases. Although SQL is an ANSI (American National Standards Institute) standard, there are different versions of the SQL language. However, to be compliant, they all support at least the major commands such as Select, Update and Delete in a similar manner. JAVASCRIPT JavaScript (often shortened to JS) is a lightweight, interpreted, object-oriented language with first class functions. JavaScript runs on the client side of the web, that can be used to design or program how the web pages behave on the occurrence of an event. JavaScript is an easy to learn and also powerful scripting language, widely used for controlling web page behaviour. JAVA Java is the foundation for virtually every type of networked…

WHAT WE’RE USING Thankfully, Python is a multi-platform programming language available for Windows, macOS, Linux, Raspberry Pi and more. If you have one of those systems, then you can easily start using Python. ◻ COMPUTER Obviously you’re going to need a computer in order to learn how to program in Python and to test your code. You can use Windows (from XP onward) on either a 32 or 64-bit processor, an Apple Mac or Linux installed PC. ◻ AN IDE An IDE (Integrated Developer Environment) is used to enter and execute Python code. It enables you to inspect your program code and the values within the code, as well as offering advanced features. There are many different IDEs available, so find the one that works for you and gives the…

Python creator Guido Van Rossum named Python after reading scripts from Monty Python’s Flying Circus. Alexa, Amazon’s Virtual Personal Assistant, uses Python to help with speech recognition. As of the end of 2018, Python was the most discussed language on the Internet. PYTHON AND LINUX SKILLS ARE THE THIRD MOST POPULAR I.T. SKILLS IN THE UK. Data analysis and Machine Learning are the two most used Python examples. Disney Pixar uses Python in its Renderman software to operate between other graphics packages. OVER 75% OF RECOMMENDED CONTENT FROM NETFLIX IS GENERATED FROM MACHINE LEARNING – CODED BY PYTHON. 90% OF ALL FACEBOOK POSTS ARE FILTERED THROUGH PYTHONCODED MACHINE LEARNING. IT’S ESTIMATED THAT OVER 75% OF NASA’S WORKFLOW AUTOMATION SYSTEMS ON-BOARD THE I.S.S. USE PYTHON. 16,000 There are over 16,000 Python…

THE POWER OF PI While having a far more powerful coding platform on which to write and test your code is ideal, it’s not often feasible. Most of us are unable to jump into a several hundred-pound investment when we’re starting off and this is where the Raspberry Pi can help out. While having a far more powerful coding platform on which to write and test your code is ideal, it’s not often feasible. Most of us are unable to jump into a several hundred-pound investment when we’re starting off and this is where the Raspberry Pi can help out. The Raspberry Pi is a fantastic piece of modern hardware that has created, or rather re-created, the fascination we once all had about computers, how they work, how to code…

STARTING PYTHON As when learning anything new, you need to start slow. You can pick up the pace as your experience grows, but for now, let’s just get something appearing on the screen. Don’t worry, you’ll soon be coding like a pro! STEP 1 Click on the Windows Start button, and start typing ‘idle’. The result will be the currently installed version of Python, IDLE (Python 3.7 32-bit), for example. You can Pin it to the Start for convenience, otherwise simply click the icon to launch the Python Shell. STEP 2 The Shell is where you can enter code and see the responses and output of code you’ve programmed into Python. This is a kind of sandbox, if you will, where you’re able to try out some simple code and…

COMMAND THE CODE Using the code we created in the previous tutorial, the one we named hello.py, let’s see how we can run code that was made in the GUI at the command line level. STEP 1 When you first installed Python, the installation routine automatically included all the necessary components to allow the execution of code outside of the GUI IDLE; in other words, the command line. To begin with, click on the Windows Start Button, and type: cmd. STEP 2 As you did when launching the Python IDLE, click on the returned result from the search, the Command Prompt App. This will launch a new window, with a black background and white text. This is the command line, also called a Terminal in macOS, Linux, and Raspberry Pi…

VARIOUS VARIABLES We’ll be working with the Python 3 IDLE Shell in this tutorial. If you haven’t already, open Python 3 or close down the previous IDLE Shell to clear up any old code. STEP 1 In some programming languages, you’re required to use a dollar sign to denote a string, which is a variable made up of multiple characters, such as a name of a person. In Python this isn’t necessary, so, for example, in the Shell enter: name=”David Hayward” (use your own name, unless you’re also called David Hayward). STEP 2 You can check the type of variable in use by issuing the type () command, placing the name of the variable inside the brackets. In our example, this would be: type (name). Add a new string variable:…

TRUE CONDITIONS Keeping conditions simple, to begin with, makes learning to program a more enjoyable experience. Let’s start then by checking if something is TRUE, then doing something else if it isn’t. STEP 1 Let’s create a new Python program that will ask the user to input a word, then check it to see if it’s a four-letter word or not. Start with File > New File, and begin with the input variable: STEP 2 Now we can create a new variable, then use the len function and pass the word variable through it to get the total number of letters the user has just entered: STEP 3 Now we’ll use an if statement to check if the word_ length variable is equal to four, and print a friendly conformation…

PLAYING WITH PI For this example, we’re going to create a program that will calculate the value of Pi to a set number of decimal places; as described by the user. It combines much of what we’ve learned, and a little more. STEP 1 Start by opening Python and creating a New File in the Editor. First, we need to get hold of an equation that can accurately calculate Pi without rendering the computer’s CPU useless for several minutes. The recommended calculation used in such circumstances is the Chudnovsky Algorithm, you can find more information about it at en.wikipedia.org/wiki/Chudnovsky_algorithm. STEP 2 We can utilise the Chudnovsky Algorithm to create our own Python script based on the calculation. We’ll begin by importing some important modules and functions within the modules: This…

THE IMMUTABLE TUPLE Reasons for having tuples vary depending on what the program is intended to do. Mostly a tuple is reserved for something special, but they’re also used, as an example, in an adventure game where non-playing character names are stored. STEP 1 A tuple is created the same way as a list, but in this instance you use curved brackets instead of square brackets. For example: STEP 2 As with lists, the items within a named tuple can be indexed according to their position in the data range: And so on. However, any attempt at deleting, or adding, to the tuple will result in an error in the Shell. STEP 3 You can create grouped tuples into lists that contain multiple sets of data. For instance, here we…

STRING FORMATTING Since Python 3, string formatting has become a much neater process, using the .format function combined with curly brackets. This makes things easier to follow and, as with most coding, there are other ways to do things but this way is recommended. STEP 1 The basic formatting in Python is to call each variable into the string using the curly brackets: STEP 2 Remember to close the print function with two sets of brackets, as you’ve encased the variable in one, and the print function in another. You can include multiple cases of string formatting in a single print function: STEP 3 We can, of course, also include integers into the mix: STEP 4 There are many different ways to apply string formatting, some are quite simple, as…

WRITE AND CLOSE The write() function is slightly more complex than read(). Along with the filename, you must also include an access mode that determines whether the file in question is in read or write mode. STEP 1 Start by opening IDLE and enter the following (obviously entering your own username location): This code will create a text file, called text.txt in write mode, using the variable ‘t’. If there’s no file of that name in the location, it will create one. If one already exits, it will overwrite it – so be careful. STEP 2 We can now write to the text file using the write() function. This works opposite to read(), writing lines instead of reading them. Try this: Note, the 109, it’s the number of characters you’ve…

LOGGING IN For this example, let’s look to a piece of code that will create user logins then allow them to log into the system, and write the time at which they logged in. We can even include an option to quit the program by pressing ‘q’. STEP 1 Let’s begin by importing the Time module, creating a new dictionary to handle the usernames and passwords, and creating a variable to evaluate the current status of the program: STEP 2 Next we need to define some functions. We can begin with creating the main menu, to where, after selecting the available options, all users will return: STEP 3 The global status statement separates a local variable from one that can be called throughout the code, this way we can use…

E = MC2 The Math module provides access to a plethora of Mathematical functions, from simply displaying the value of Pi, to helping you create complex 3D shapes. STEP 1 The Math module is built-in to Python 3; so there’s no need to PIP install it. As with the other modules present, you can import the module’s function by simply entering import math into the Shell, or as part of your code in the Editor. STEP 2 Importing the Math module, as such, will give you access to the module’s code. From there, you can call up any of the available functions within Math, by using math, followed by the name of the function in question. For example, enter: math.sin(2) This will display the sine of 2. STEP 3 As…

PYGAMING As stated, Pygame isn’t an inherent module to Python. Those using the Raspberry Pi will already have it installed. Everyone else will need to use pip install pygame from the command prompt. STEP 1 Naturally, we need to load up the Pygame modules into memory before we’re able to utilise them. Once that’s done, Pygame requires the user to initialise it prior to any of the functions being used: STEP 2 Let’s create a simple, game ready window and give it a title: You will notice that after the first line is entered, you’ll need to click back into the IDLE Shell to continue entering code. In addition, you can change the title of the window to anything you like. STEP 3 Sadly, you can’t close the newly created…

Linux is a flexible and powerful operating system but it also has a unique filesystem and way of doing things. Therefore, learning how Linux works is essential to creating better Python code. You’ll find that Linux already has Python elements built-in and if you’re working on a Raspberry Pi 4, then everything you need to code with Python is ready from the start. In this section we will mainly focus on using the Raspberry hardware with Linux but regardless of whether you’re using an RPi, Linux Mint, or Ubuntu, these pages will prove invaluable for your Python learning.…

GETTING AROUND To drop into the Terminal, click on the fourth icon from the left along the top of the Raspberry Pi desktop, the one with a right-facing arrow and an underscore. This is the shell, or Terminal. STEP 1 First, you’re going to look at directories and the directory path. A directory is the same thing as a folder, however in Linux it’s always called a directory. These are placed inside each other using a “/” character. So when you see / home/pi it means the pi directory is inside the home directory. Enter: clear and press return to clean the screen. Now enter: pwd. This stands for Print Working Directory and displays /home/pi.. STEP 2 When you log in to your Raspberry Pi, you don’t start at the…

MANAGING FILES AND DIRECTORIES Now that you know how to create files, you’ll want to learn how to make directories, which are the same thing as folders, as well as move items around. If you are more used to working with a desktop interface, this can take a bit of getting used to. STEP 1 Enter: ls to quickly view all the directories currently in in the home location. Directories are created using the “mkdir” command (make directory). Enter: mkdir testdir to create a new directory in your home directory. Enter: ls again to see it. STEP 2 The “mkdir” command is different to touch, in that it doesn’t update the timestamp if you use it with a directory that already exists. Enter: mkdir testdir again and you’ll get the…

THE JOY OF TEXT To be able to edit or create a text file, you need a good text editor. Linux has many but here are some in action on the Raspberry Pi. STEP 1 The first text editor for the Raspberry Pi is the default desktop environment app: Leafpad. To use, you can either double-click an existing text file or click the Raspberry Pi menu icon (in the top left of the desktop) and from the Accessories menu, choose Text Editor. STEP 2 From the Terminal there are even more options, although using the correct command, you can launch any of the desktop apps via the Terminal. One of the simplest, and a classic text editor that’s carried over from the Unix days, is vi. In the Terminal, enter:…

LOTS OF LINUX Linux is a huge and versatile command line language and there are hundreds of commands you can learn and use. Here are a few that can help you get more from your Raspberry Pi. STEP 1 The Raspberry Pi is a great little computer, so let’s start by getting some information. Enter: cat /proc/cpuinfo to view some details on your Raspberry Pi processors. If you have a Raspberry Pi 3 you will see four processors, along with the model name and other info. STEP 2 Remember that cat is used to list the contents of a text file, which is what cpuinfo is. There are other text files with system info available. Try “cat / proc/meminfo” to get information about your memory, “cat / proc/partitions” for information…

TERMINAL FUN All these commands are Linux-based, so not only can you use them on the Raspberry Pi but also on any of the Debian-based Linux distributions. STEP 1 The first command we’re going to use is sl, it’s not installed by default so enter: sudo apt-get install sl. The command can be run with sl and when executed displays a Steam Locomotive travelling across the screen (hence ‘sl’). Entering: LS (note the upper case) also works. STEP 2 Fans of Star Wars even get a fix when it comes to the Terminal. By linking to a remote server via the telnet command, you can watch Episode IV: A New Hope being played out, albeit in ASCII. To view this spectacle, enter: sudo apt-get install telnet, followed by: telnet towel.…

TOP 10 COMMANDS These may not be the most common commands used by everyone but they will certainly feature frequently for many users of Linux and the command line. cd The cd command is one of the commands you will use the most at the command line in Linux. It allows you to change your working directory. You use it to move around within the hierarchy of your file system. You can also use chdir. ls The ls command shows you the files in your current directory. Used with certain options, it lets you see file sizes, when files where created and file permissions. For example, ls ~ shows you the files that are in your home directory. cp The cp command is used to make copies of files and…

1 This part of the code imports the necessary modules. The OS and Subprocess modules deal with the operating system elements of the program. 2 Each def XXX() functions store the code for each of the menu’s options. Once the code within the function is complete, the code returns to the main menu for another option. 3 This is part of the code that checks to see what OS the user is running. In Windows the CLS command clears the screen, whereas in Linux and macOS, the Clear command wipes the screen. If the code tries to run CLS when being used in Linux or macOS, an error occurs, which then prompts it to run the Clear command instead. 4 These are the options, from 1 to 12. Each executes…

TXTROT.PY Here we’ve introduced several examples of displaying text within the Pygame module. Each is easily recognised within the code, so you can pull it out and use it in your code. The Joy Of Text Here, you can see that we’ve started by defining the colours but left the text black throughout the rest of the code; then, also left the display window with a white background. The code itself is fairly easy to follow and you can improve it by using different colours, changing the font for each text example, and its size too. Try using some of the text examples individually in your code as an introduction to your program perhaps. Either way you use it, it will help make it stand out a little more than…

ADVENTURE.PY The Adventure game uses just the Time module to begin with, creating pauses between print functions. There’s a help system in place to expand upon, as well as the story itself. Adventure Time This, as you can see, is just the beginning of the adventure and takes up a fair few lines of code. When you expand it, and weave the story along, you’ll find that you can repeat certain instances such as a chance meeting with an enemy or the like. We’ve created each of the two encounters as a defined set of functions, along with a list of possible choices under the cmdlist list, and cmd variable, of which is also a defined function. Expanding on this is quite easy, just map out each encounter and choice…

EPICSCROLL.PY We’ve used the poem Cimmeria by Robert E. Howard for the code’s scrolling text, along with a dramatic black background and red text. We think you’ll agree, it’s quite epic. A Long Time Ago… The obvious main point of enhancement is the actual text itself. Replace it with a list of credits, or an equally epic opening storyline to your Python game, and it will certainly hit the mark with whoever plays it. Don’t forget to change the screen resolution if needed; we’re currently running it at 800 x 600.…

CALCULATOR.PY We created some function definitions to begin with, then lead on to the user menu and inputs. It’s an easy piece of code to follow and as such can also be expanded well too. Improved Calculations The obvious contender for improvement here is using the Create Your Own Modules route and extracting the function definitions as a module. You can then call the module and focus on the body of the code. The other area of improvement is code itself. Where there’s just a single shot at making a calculation, you could encase it in a while loop, so once a value is presented the user is sent back to the main menu. Perhaps, improvement to the Invalid Input section is worth looking into as well.…

We’re going to finish off by looking at some interesting coding elements that you can incorporate into your own unique projects and code. In this section you’ll find code for creating a loading screen for your content, text animations using ASCII art, clever ways in which you can include animated sections at the command prompt, and even code that can track the International Space Station in realtime, while displaying both the astronauts on board and its current latitude and longitude. There are also pages of common, and language specific, mistakes to help you avoid, and create, error-free and effective code in the future.…

THE GRAPHICS Firstly, we need to get hold of a map of the world, and an image of the ISS to use as an icon, that will be updated according to the position of the space station as it travels over the surface. A quick Google of World Map will help you out here. Look for one that’s reasonably large, the one we used for this example was 1280 x 700, and one that has the names of the countries – if you’re using this with young people, to help with putting shapes of countries to names. Next, look for an ISS icon. As this is going to be a graphical representation of the location of the ISS, we need the image to be reasonably small so it doesn’t drown…

THE WINDOWS WAY The two systems use moderately different ways to accomplish the same task, Windows is slightly easier (by a single command), and so we’ll start there. STEP 1 Let’s begin by creating a sample folder within your Python directory; call it batpy, for example. Within the batpy folder, create a new text file and enter the following: STEP 2 We won’t go into the intricacies of Windows batch files here. Suffice to say this code will ask for a user’s name, store the name as a variable called name, display a message, then open the Python code we’re about to create. We need to save the file as a batch file, click File > Save As, call it batpy1.bat and set Save As Type as All Files. STEP…

Argument The detailed extra information used by Python to perform more detailed commands. Can also be used in the command prompt to specify a certain runtime event. Block Used to describe a section or sections of code that are grouped together. Break A command that can be used to exit a for or while loop. For example, if a key is pressed to quit the program, Break will exit the loop. Class A class provides a means of bundling data and functionality together. They are used to encapsulate variables and functions into a single entity. Comments A comment is a section of real world wording inserted by the programmer to help document what’s going on in the code. They can be single line or multi-line and are defined by a…