Indholdsfortegnelse for Vol 9 2024 i Coding User

A Python module is a Python-created source file that contains the necessary code for classes, functions and global variables. You can bind and reference modules to extend functionality, and create even more spectacular Python programs. Are you curious about how to improve your use of these modules to add a little something extra to your code? Then read on and learn how they can be used to fashion fantastic code with graphics, animations and operating system specific commands.…

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 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: This displays the sine of 2. STEP 3 As you will no doubt…

Despite how close AI and ML are, there are distinct differences between the two technologies. AI refers to the study of how to train a computer to accomplice the things that humans can do significantly better and faster. Whereas, ML is the ability for a computer to learn from its experiences, so that the outcome and performance will eventually become more accurate and accomplished. While different, they are both essentially discussing the same element: training a system to learn and do things independently. Where AI is said to lead to wisdom, ML reportedly leads to knowledge and, thanks to Python, that gap is getting closer every day. APPLICATIONS Both AI and ML are hugely present in today’s technology. Where, just a few years ago, most of us associated AI with…

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…

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…

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…

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 about your…

LIGHTS, CAMERA, ACTION The Tkinter module is an ideal starting point for 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 a canvas (window) and the ball to animate: STEP 2 Save and Run the code. You will see a blank window appear, with a red ball sitting in the upper left corner of the window. While this is 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…

We’ve included a vast Python code repository for you to freely use in your own programs. There’s plenty in here to help you create a superb piece of programming, or extend your project ideas. We’ve got code for making backups of your files and folders, 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. We’ve broken down some of the newer, and extended, concepts of the code to help you better understand what’s going on. This way you can easily adapt it to your own uses. 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…

RNDNUMGEN.PY It might be simple but this little piece of code will ask the user for two sets of numbers, a start and a finish. The code will then pluck out a random number between the two sets and display it. More Input While an easy code to follow, it could be more interesting if you prompt the user for more input. Perhaps you can provide them with addition, subtraction, multiplication elements with their numbers. If you’re feeling clever, see if you can pass the code through a Tkinter window or even the Ticker window that’s available on Page 16. Furthermore, the core of the code can be used in a text adventure game, where the character fights something and their health, along with the enemy’s, is reduced by a…

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.…

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…

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…

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 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 base of the hard drive, known as the ‘root’ (also known…

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…

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…

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 very 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…

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 labelled ‘s’. The ticker example can be used for system warnings, perhaps something that will display across your work or home…

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…

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:…

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…