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Manage a course's grade database with email-based communication.

Project Description

pygrader is a directory-based grade database for grading course assignments. Besides tracking grades locally, you can also use it to automatically mail grades to students and professors associated with the course. For secure communication, PGP can be used to sign and/or encrypt any of these emails.




I’ve packaged pygrader for Gentoo. You need layman and my wtk overlay. Install with:

# emerge -av app-portage/layman
# layman --add wtk
# emerge -av dev-python/pygrader


If you’re installing by hand or packaging pygrader for another distribution, you’ll need the following dependencies:

Package Purpose Debian Gentoo
Jinja email templating python-jinja2 dev-python/jinja
pgp-mime secure email   dev-python/pgp-mime [#pm]
nose testing (optional) python-nose dev-python/nose
NumPy statistics (optional) python-numpy dev-python/numpy

If NumPy is not installed, we’ll fall back to internal implementations of the various statistical calculations.

If you are developing pygrader, you can use update-copyright to keep the copyright blurbs up to date.

[1]In the wtk overlay.

Installing by hand

pygrader is available as a Git repository:

$ git clone git://

See the homepage for details. To install the checkout, run the standard:

$ python install


pgp-mime depends on pyassuan, which requires Python 3.3. If your distribution doesn’t package Jinja or pgp-mime for Python 3.3, you can use pygrader’s Git submodules to easily fetch compatible versions. The submodules are stored in the dep/src directory with symbolic links in dep itself. For example, the pgp-mime submodule is kept in dep/src/pgp-mime with the symlink dep/pgp_mime pointing to dep/pgp-mime/pgp_mime. If you only need a few submodules, you can initialize them explicitly:

$ git submodule init pgp-mime pyassuan

If you want all of the submodules, use:

$ git submodule init

Git submodule will fetch (when necessary) and unpack the gitlinked commit of initialized submodules with:

$ git submodule update

You’ll want to run update again after any superproject (in this case, pygrader) action that updates the gitlinks. Once you have checked out the dependencies you need, point PYTHONPATH to the dep directory whenever you run pygrader. For example:

$ PYTHONPATH=dep ./bin/ ...


Pygrader will help keep you organized in a course where the students submit homework via email, or the homework submissions are otherwise digital (i.e. scanned in after submission). You can also use it to assign and manage any type of grade via email. In the following sections, I’ll walk you through local administration for the test course.

All of the processing involves using the command. Run:

$ --help

for details.

Sending email

Pygrader receives submissions and assigns grades via email. In order to send email, it needs to connect to an SMTP server. See the pgp-mime documentation for details on configuring you SMTP connection. You can test your SMTP configuration by sending yourself a test message:

$ -VVV smtp -a -t

Defining the course

Once you’ve got email submission working, you need to configure the course you’ll be grading. Each course lives in its own directory, and the basic setup looks like the test example distributed with pygrader. The file that you need to get started is the config file in the course directory:

$ cat test/course.conf
name: Physics 101
assignments: Attendance 1, Attendance 2, Attendance 3, Attendance 4,
  Attendance 5, Attendance 6, Attendance 7, Attendance 8, Attendance 9,
  Assignment 1, Assignment 2, Exam 1, Exam 2
robot: Robot101
professors: Gandalf
assistants: Sauron
students: Bilbo Baggins, Frodo Baggins, Aragorn

[Attendance 1]
points: 1
weight: 0.1/9
due: 2011-10-03

[Attendance 2]
points: 1
weight: 0.1/9
due: 2011-10-04


[Assignment 1]
points: 10
weight: 0.4/2
due: 2011-10-10
submittable: yes


[Exam 2]
points: 10
weight: 0.4/2
due: 2011-10-17

nickname: phys-101 robot
pgp-key: 4332B6E3

nickname: G-Man
pgp-key: 4332B6E3


[Bilbo Baggins]
nickname: Bill


The format is a bit wordy, but it is also explicit and easily extensible. The time it takes to construct this configuration file should be a small portion of the time you will spend grading submissions.

If a person has the pgp-key option set, that key will be used to encrypt messages to that person and sign messages from that person with PGP. It will also be used to authenticate ownership of incoming emails. You’ll need to have GnuPG on your local host for this to work, and the user running pygrader should have the associated keys in their keychain.

The course.robot option defines a dummy person used to sign automatically generated emails (e.g. responses to mailpipe-processed submissions).

The submittable option marks assignments that accept direct submission from students (e.g. homeworks). You probably don’t want to set this option for attendance, since it would allow students to mark themselves as having attended a class. submittable default to False.

Processing submissions

As the due date approaches, student submissions will start arriving in your inbox. Use’s mailpipe command to sort them into directories (using the pygrader.handler.submission handler). This will also extract any files that were attached to the emails and place them in that person’s assignment directory:

$ -d test mailpipe -m maildir -i ~/.maildir -o ./mail-old

Use’s todo command to check for ungraded submissions:

$ -d test todo mail grade

Then create grade files using your favorite editor. The first line of the grade file should be the student’s grade for that assigment, expressed in a syntax that Python’s float() understands (1, 95, 2.5, 6.022e23, etc.). If you wish, you may add additional comment lines after the grade line, offering suggestions for improvement, etc. This comment (if present) will be mailed to the student along with the grade itself. There are a number of example grade files in the test directory in pygrader’s Git source.

To see how everyone’s doing, you can print a table of grades with’s tabulate command:

$ -d test tabulate -s

When you want to notify students of their grades, you can send them all out with’s email command:

$ -d test email assignment 'Exam 1'

Mailpipe details

Besides accepting student submissions from incoming email, mailpipe also accepts other types of requests, and can be configured to respond automatically:

  • Incoming student assignment submissions are archived (see the submit command).
  • Students can check their grades without having to bother anyone (see the get commands).
  • Professors and teaching assistants can request student submissions so that they can grade them (see the get commands).
  • Professors and TAs can request the grades for the entire class (see the get commands).
  • Professors and TAs can assign grades (see the grade command).

To enable automatic responses, you’ll need to add the -r or --respond argument when you call

If you get tired of filtering your inbox by hand using mailpipe, you can (depending on how your mail delivery is setup) use procmail to automatically run mailpipe automatically on incoming email. There is an example .procmailrc in the pygrader.mailpipe.mailpipe docstring that runs mailpipe whenever incoming emails have [phys160:submit] in their subject somewhere.

The use of [TARGET] tags in the email subject allows users to unambiguously specify the purpose of their email. Currently supported targets include (see the handlers argument to pygrader.mailpipe):


student assignment submission. The remainder of the email subject should include the case insensitive name of the assignment being submitted (see pygrader.handler.submission._match_assignment). An example subject would be:

[submit] assignment 1

request information from the grade database. For students, the remainder of the email subject is irrelevant. Grades and comments for all graded assignments are returned in a single email. An example subject would be:

[get] my grades

Professors and TAs may request either a table of all grades for the course (à la tabulate), the full grades for a particular student, or a particular student’s submission for a particular assignment. Example subjects are (respectively):

[get] don’t match any student names [get] Bilbo Baggins [get] Bilbo Baggins Assignment 1

professors and TAs can submit a grade for a particular student on a particular assignment. The body of the (possibly signed or encrypted) email should be identical to the grade file that the sender wishes to create. An example subject would be:

[grade] Bilbo Baggins Assignment 1

To allow you to easily sort the email, you can also prefix the target with additional information (see pygrader.mailpipe._get_message_target). For example, if you were running several courses from the same email account, you’d want a way for users to specify which course they were interacting with so you could filter appropriately in your procmail rules. Everything in the subject tag before an optional semicolon is ignored by mailpipe, so the following subjects will be handled identically:

[submit] assignment 1
[phys101:submit] assignment 1
[phys101:section2:submit] assignment 1


Run the internal unit tests using nose:

$ nosetests --with-doctest --doctest-tests pygrader

If a Python-3-version of nosetests is not the default on your system, you may need to try something like:

$ nosetests-3.2 --with-doctest --doctest-tests pygrader


This project is distributed under the GNU General Public License Version 3 or greater.


W. Trevor King

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