Contributing code

The preferred way to contribute to HazImp is to fork the main repository on GitHub:

  1. Fork the project repository: click on the ‘Fork’ button near the top of the page. This creates a copy of the code under your account on the GitHub server.

  2. Clone this copy to your local disk (using ssh commands):

    $ git clone
    $ cd hazimp
  3. Create a branch to hold your changes:

    $ git checkout -b my-feature

    and start making changes. Never work in the master branch!

  4. Work on this copy on your computer using Git to do the version control. When you’re done editing, do:

    $ git add modified_files
    $ git commit

    to record your changes in Git, then push them to GitHub with:

    $ git push -u origin my-feature

Finally, go to the web page of the your fork of the hazimp repo, and click ‘Pull request’ to send your changes to the maintainers for review. This will send an email to the committers. Pull requests should only be made against the ‘develop’ branch of the repository. Pull requests against the ‘master’ branch will be refused and requested to resubmit against the ‘develop’ branch.

A demonstration of the git workflow used for HazImp can be seen at

(If any of the above seems like magic to you, then look up the Git documentation on the web.)

It is recommended to check that your contribution complies with the following rules before submitting a pull request:

  • All public methods should have informative docstrings with sample usage presented as doctests when appropriate.

  • When adding additional functionality, provide at least one example script in the examples/ folder. Have a look at other examples for reference. Examples should demonstrate why the new functionality is useful in practice.

  • At least one paragraph of narrative documentation with links to references in the literature (with PDF links when possible) and an example.

  • Include clear provenance statements in any new functionality that generates output, using the ‘prov’ library.

You can also check for common programming errors with the following tools:

  • Code with good unittest coverage, check with:

    $ pip install nose coverage
    $ nosetests --with-coverage tests/
  • No pyflakes warnings, check with:

    $ pip install pyflakes
    $ pyflakes path/to/
  • No PEP8 warnings, check with:

    $ pip install pep8
    $ pep8 path/to/
  • AutoPEP8 can help you fix some of the easy redundant errors:

    $ pip install autopep8
    $ autopep8 path/to/


A great way to start contributing to HazImp is to pick an item from the list of Issues in the issue tracker. Resolving these issues allow you to start contributing to the project without much prior knowledge. Your assistance in this area will be greatly appreciated by the more experienced developers as it helps free up their time to concentrate on other issues.


We use sphinx-doc for creating documentation for HazImp. reStructuredText files are stored in the docs folder, while function docstrings are embedded in the code base.

Running Sphinx

If using a conda environment to run HazImp, users may need to set the SPHINXBUILD environment variable to point to the correct sphinx-build.exe executable.

To build the HTML pages on your local computer, use the make html command.

On Windows:

set SPHINXBUILD=%CONDAPATH%\envs\hazimp\Scripts\sphinx-build.exe
make html

On bash:

export SPHINXBUILD=$CONDAPATH/envs/hazimp/scripts/sphinx-build
make html

Check the output for any error messages, then open the created docs in _build/html/index.html.

See the sphinx-doc pages for more details on using Sphinx Python Documentation Generator.