% Interaction Technology and Techniques Assignment 1: Linux, Python % Summer Semester 2021 % Submission due: Wednesday, 21. April 2021, 23:55

We want everyone to have a working development environment and a (very) basic grasp of the Python language by next week. Therefore, this assignment needs to be done individually, not in groups.

Please check out the general rules for assignments documented in the introductory slides!

1.1: Set up your development environment

First you should set up a working Linux system.

• Download the Debian testing (aka bullseye) netinst CD image (you'll probably want the amd64 version): http://cdimage.debian.org/cdimage/weekly-builds/

• Install Debian either on a disk or inside a virtual machine:

  • virtual machine: install VirtualBox, create a new virtual machine, mount the image file as CD-ROM and boot the virtual machine.
  • hard disk: burn the image file to a CD or copy it to an USB stick using dd; boot from the CD/USB stick.

• Follow the installation instructions (We recommend using "Install" instead of "Graphical Install") and choose the default settings if not sure.

  • Please select English (US) as default language as this makes following the tutorials easier
  • When asked about the desktop environment to be installed, keep the default "MATE" (a very simple one) for now or select one that you prefer.
  • If the installer shows an error message during download/installation of the software, retry several times, check that your network connection is ok, and finally allocate more RAM to the virtual machine.

• Once the system has booted, log into the desktop and open a terminal (Menu / System Utilities). Customize your system a little bit:

  • You have to change to the root user for installing additional packages: $ su (the dollar sign is the prompt and has not to be typed in). Enter the root password you assigned earlier in the installation process. The prompt will change to #.
  • Alternatively, you may add your user to the "sudo" group (adduser franz sudo) and prefix all "root" commands with sudo instead of using su.
  • Many useful packages are not available by default because they contain non-free software. You need to edit the list of package repositories to make them available:
    • # nano /etc/apt/sources.list
    • Change the line with your primary repository to also include "contrib" and "non-free": (deb http://ftp.debian.com/debian/ bullseye main contrib non-free or similar).
    • Save (Ctrl-o) and exit the editor (Ctrl-x).
    • Run # apt update in order to get the new package lists.
  • The root user does not have autocompletion of package names enabled. Execute source /etc/bash_completion to enable it. Now you can type apt install virtualb<TAB> and all available packages starting with "virtualb" are shown.
  • If inside VirtualBox, install the guest additions: # apt install virtualbox-guest-utils virtualbox-guest-dkms virtualbox-guest-x11 and reboot.
  • Install the necessary Python packages for the next few sessions. The following ones are the most important ones: # apt install python3 python3-doc ipython3 jupyter-notebook python3-matplotlib python3-numpy python3-scipy python3-virtualenv python3-pip python3-pyqt5 python3-pyqtgraph pep8 python3-sklearn python3-pandas.
  • Install a few other nice tools: xsel zenity apt-file
  • Install an editor or IDE of your choice. Some suggestions:
    • lightweight: vim + plugins
    • simple IDE: Komodo Edit
    • full IDE: PyCharm Edu or Komodo IDE
    • more suggestions on the Python wiki: Editors, IDEs
  • on mac host you have to capture the mouse for wiimote/hardware cursor override (this is probably needed later) Make yourself familiar with the environment:

• read the tutorials linked on the course page

• learn how to use the command line: tab completion, history, shortcuts

• read the man pages for all commands listed on the Linux handout

• learn how to search for and install packages using apt-cache search $keywords, apt-cache show $packagename, apt install $packagename apt-file search $filename

• build a few simple shell one-liners using pipes

Hand in the following Bash script:

count.sh which does the following:

• download a text file from ftp://sunsite.informatik.rwth-aachen.de/pub/mirror/ibiblio/gnome/README if it is not yet present in the current directory (use wget for this)
• make all text lowercase (use tr)
• split it into individual words per line (use cat and/or sed for this)
• alphabetically sort the list of words and remove duplicates (sort and uniq, possibly also grep).
• print out the 10 most common words in the text (without number of occurrences) on stdout (uniq, sort, and head)

Points

• 2 The shell script has been submitted, is not empty, and does not print out error messages.
• 1 The script works as expected.
• 1 The script is well structured.
• 1 The script includes comments for every line.
• 1 The script removes punctuation, capitalization, etc. before counting the words.

1.2: Basic Python I/O

• read the Python 3.9 documentation at https://docs.python.org/3/
• read the Python style guide (PEP 8) at http://legacy.python.org/dev/peps/pep-0008/ and try out the pep8 tool on your code.
• read the tutorials linked on the course page
• start jupyter notebook and get comfortable with it - you should use it to document your algorithms later in the course.
• write a few python scripts
• try out as many of the built-in functions (https://docs.python.org/3/library/functions.html) as possible.
• experiment with the most important built-in types: int, float, str(ing), tuple, list, dict, set
• play with the % string formatting syntax
• get familiar with a few basic modules, such as: sys, math, random.

Hand in the following Python program:

stats.py: Reads in a list of floating point numbers either from a textfile passed as an argument to the script or via stdin. Numbers are separated by space characters and may contain either , or . as decimal separator. Prints out the mean, median, and standard deviation for these on stdout.

The script should only use built-in commands, the math module (for math.sqrt()), and the sys module (for sys.argv and sys.stdin).

Points

• 1 The python script has been submitted, is not empty, and does not print out error messages.
• 3 The script correctly calculates mean, median, and standard deviation (numbers may be hardcoded)
• 2 The script can read and convert numbers from both a file and ''stdin''.
• 2 The script is well-structured and follows the Python style guide (PEP 8)

1.3: Drawing with the ''turtle'' module

Get to know the turtle module (https://docs.python.org/3/library/turtle.html).

Hand in the following Python program:

circle.py: Takes a radius (int) as commandline parameter. Draws something resembling a circle with the given radius using the turtle module. The turtle should alternatively move forward or turn left/right so that it stays at about radius pixels from the center of the screen. Experiment with varying turning angles and movement distances. Do not use the circle() function - that would be too easy.

Points

• 1 The python script has been submitted, is not empty, and does not print out error messages.
• 2 The script draws a circle-like structure on the screen.
• 2 The script draws a beautiful circle-like structure on the screen.
• 1 The script is well-structured and follows the Python style guide (PEP 8)

1.4: The most *ing things you learned

Prepare a list of the most interesting, surprising, or annoying features/bugs you discovered while doing the other assignments. Bring this list to the next course session.

Submission

Submit via GRIPS until the deadline:

• count.sh
• stats.py
• circle.py

All files should use UTF-8 encoding and Unix line breaks. Python files should use spaces instead of tabs.

                                                           Have Fun!