Python Turtle for Dodona

Python Turtle graphics is a popular way for introducing programming to kids. This judge aims to provide feedback for these students during the learning experience and evaluations. How similar is the submission of the student to the solution of the teacher?

This Dodona course contains some sample exercises that were used in developing the Python Turtle judge:

• https://dodona.ugent.be/en/courses/1468/

There are a number of sample exercises on Dodona's sample exercises repository to demonstrate the use of the judge:

• https://github.com/dodona-edu/example-exercises # TODO

Judge features

• Comparison based on solution Python file
• Submission and solution image shown side-by-side
• Absolute difference and percentage of mismatched visible (non-transparant) pixels
• Option to set custom canvas size in config.json
• Feedback in language of user (Dutch or English)

Judge properties

• print() statements and time.sleep() are ignored.
• No intermediary steps ar shown. Only the end result is compared.
• Judge accepts solution independent of code. The judge doesn't make a destination between e.g. square drawn with for-loop or not. If a figure is drawn clockwise or counterclockwise it's treated equally.
• Support for transparency.
• Script available to convert solution.py to svg image for exercise description.

Table of Contents

• Recommended exercise directory structure
• Recommended dirconfig.json
• Recommended config.json (example with default settings)
• Optional evaluation settings in config.json
• Generator script
• Contributors

Recommended exercise directory structure

More info about repository directory structure

Add your solution file (solution.py) the evaluation folder. You can define a different name for the solution in the config.json file. Absolute necessary files are marked with ▶ in the tree structure below.

+-- README.md                            # Optional: Describes the repository
+-- dirconfig.json                       # Shared config for all exercises in subdirs
+-- 📂public                            # Optional: Contains files that belong to the course or series
|   +-- my_turtle.png                    # Optional: An image to reuse throughout the course
+-- 📂turtle-exercises                  # We could group exercises in a folder
|   +-- 📂rectangle                     # Folder name for the exercise
|   |   +-- config.json                  # ▶ Configuration of the exercise (explained later)
|   |   +-- 📂evaluation                # -- 🔽️ ADD YOUR SOLUTION HERE 🔽 --
|   |   |   +-- solution.py              # ▶ The Python Turtle model solution file
|   |   +-- 📂solution                  # Optional: This will be visible in Dodona for teachers
|   |   |   +-- solution.py              # Optional: The Python Turtle model solution file
|   |   +-- 📂description               #
|   |       +-- description.nl.md        # ▶ The description in Dutch
|   |       +-- description.en.md        # Optional: The description in English
|   |       +-- 📂media                 # Optional folder
|   |       |   +-- rectangle.svg       # Optional: An image used in the description
|   |       +-- 📂boilerplate           # Optional folder
|   |           +-- boilerplate          # Optional: loaded automatically in submission text area
|   :
:

Recommended dirconfig.json

More info about exercise directory structure

{
    "type": "exercise",
    "programming_language": "python",
    "access": "public",
    "evaluation": {
        "handler": "turtle",
        "time_limit": 10,
        "memory_limit": 50000000
    },
    "labels": [
        "turtle"
    ],
    "author": "Firstname Lastname <firstname_lastname@ugent.be>",
    "contact": "firstname_lastname@ugent.be"
}

Recommended config.json (example with default settings)

{
    "description": {
        "names": {
            "nl": "Mijn eerste Python Turtle oefening",
            "en": "My first Python Turtle exercise"
        }
    },
    "type": "exercise",
    "programming_language": "turtle",
    "access": "public",
    "labels": [
        "turtle"
    ],
    "evaluation": {
        "handler": "turtle",
        "canvas_width": 400,
        "canvas_height": 250
    }
}

Optional evaluation settings in config.json

If these settings are not defined, the default value is chosen.

Evaluation setting	Description	Possible values	Default
solution_file	Relative path to solution file	path	./solution.py
canvas_width	Width of canvas in pixels	int	400
canvas_height	Height of canvas in pixels	int	250

Generator script

The svg images for each exercise can be made with a Python script. Place the script at the root of your folder with exercises.

# TODO, see https://github.com/BTWS2/judge-turtle/issues/16

Show svg image in Dodona description

• Markdown (recommended)

![image_name](./media/image_name.svg){:height="50%" width="50%"}{: style="border-style: inset"}

• HTML

<img src="./media/image_name.svg" alt="image_name" height="50%" width="50%" style="border-style: inset">

Contributors

• T. Ramlot
• Don Kirkby (author of svg-turtle)
• B. Willems

Development funded by the Faculty of Engineering and Architecture of Ghent University