Tutorial

This tutorial can help you to verify that you have installed Otter correctly and introduce you to the general Otter workflow. Once you have installed Otter, download this zip file and unzip it into some directory on your machine; you should have the following directory structure:

tutorial
├── demo.ipynb
├── requirements.txt
└── submissions
    ├── ipynbs
    │   ├── demo-fails1.ipynb
    │   ├── demo-fails2.ipynb
    │   ├── demo-fails2Hidden.ipynb
    │   ├── demo-fails3.ipynb
    │   ├── demo-fails3Hidden.ipynb
    │   └── demo-passesAll.ipynb
    └── zips
        ├── demo-fails1.zip
        ├── demo-fails2.zip
        ├── demo-fails2Hidden.zip
        ├── demo-fails3.zip
        ├── demo-fails3Hidden.zip
        └── demo-passesAll.zip

This section describes the basic execution of Otter’s tools using the provided zip file. It is meant to verify your installation and to loosely describe how a few Otter tools are used. This tutorial covers Otter Assign, Otter Generate, and Otter Grade.

Otter Assign

Start by moving into the tutorial directrory. This directory includes the master notebook demo.ipynb. Look over this notebook to get an idea of its structure. It contains five questions, four code and one Markdown (two of which are manually-graded). Also note that the assignment configuration in the first cell tells Otter Assign to generate a solutions PDF and an autograder zip file and to include special submission instructions before the export cell. To run Otter Assign on this notebook, run

otter assign demo.ipynb dist

Otter Assign should create a dist directory which contains two further subdirectories: autograder and student. The autograder directory contains the Gradescope autograder, solutions PDF, and the notebook with solutions. The student directory contains just the sanitized student notebook.

tutorial/dist
├── autograder
│   ├── autograder.zip
│   ├── demo-sol.pdf
│   ├── demo.ipynb
│   ├── otter_config.json
│   └── requirements.txt
└── student
    └── demo.ipynb

For more information about the configurations for Otter Assign and its output format, see Creating Assignments.

Otter Generate

In the dist/autograder directory created by Otter Assign, there should be a file called autograder.zip. This file is the result of using Otter Generate to generate a zip file with all of your tests and requirements, which is done invisibly by Otter Assign when it is used (which it is configured to do in the assignment metadata). Alternatively, you could generate this zip file yourself from the contents of dist/autograder by running

otter generate

in that directory (but this is not recommended).

Otter Grade

Note: You should complete the Otter Assign tutorial above before running this tutorial, as you will need some of its output files.

At this step of grading, the instructor faces a choice: where to grade assignments. The rest of this tutorial details how to grade assignments locally using Docker containers on the instructor’s machine. You can also grade on Gradescope or without containerization, as described in the Executing Submissions section.

Let’s now construct a call to Otter that will grade these notebooks. We will use dist/autograder/autograder.zip from running Otter Assign to configure our grading image. Our notebooks are in the ipynbs subdirectory and contain a couple of written questions, so we’ll specify the --pdfs flag to indicate that Otter should grab the PDFs out of the Docker containers. Lastly, we’ll name the assignment demo with the -n flag.

Let’s run Otter on the notebooks:

otter grade -n demo -a dist/autograder/demo-autograder_*.zip --pdfs -v submissions/ipynbs

(The -v flag is so that we get verbose output.) After this finishes running, there should be a new file and a new folder in the working directory: final_grades.csv and submission_pdfs. The former should contain the grades for each file, and should look something like this:

file,q1,q2,q3
fails3Hidden.ipynb,1.0,1.0,0.5
passesAll.ipynb,1.0,1.0,1.0
fails1.ipynb,0.6666666666666666,1.0,1.0
fails2Hidden.ipynb,1.0,0.5,1.0
fails3.ipynb,1.0,1.0,0.375
fails2.ipynb,1.0,0.0,1.0

Let’s make that a bit prettier:

file	q1	q2	q3
fails3Hidden.ipynb	1.0	1.0	0.5
passesAll.ipynb	1.0	1.0	1.0
fails1.ipynb	0.6666666666666666	1.0	1.0
fails2Hidden.ipynb	1.0	0.5	1.0
fails3.ipynb	1.0	1.0	0.375
fails2.ipynb	1.0	0.0	1.0

The latter, the submission_pdfs directory, should contain the filtered PDFs of each notebook (which should be relatively similar).

Otter Grade can also grade the zip file exports provided by the Notebook.export method. All we need to do is add the --ext flag to indicate that the submissions are zip files. We have provided some example submissions, with the same notebooks as above, in the zips directory, so let’s grade those:

otter grade -n demo -a dist/autograder/demo-autograder_*.zip -v --ext zip submissions/zips

This should have the same CSV output as above but no submission_pdfs directory since we didn’t tell Otter to generate PDFs.

You can learn more about the grading workflow for Otter in this section.