Latest PyPI version

Python 3 (>=3.9) must be installed before you can install IOData. In addition, IOData has the following dependencies:

Normally, you don’t need to install these dependencies manually. They will be installed automatically when you follow the instructions below.

  1. The cleanest option is to install IOData in a virtual environment:

    # Create a virtual environment in ~/horton3
    # Feel free to change the path.
    python3 -m venv ~/horton3
    # Activate the virtual environment.
    source ~/horton3/bin/activate
    # Install IOData in the venv horton3.
    pip3 install qc-iodata
    # alternative: python3 -m pip install qc-iodata
    # For developers, install with developer dependencies
    pip3 install qc-iodata[dev]
    # alternative: python3 -m pip install qc-iodata[dev]

    The source command needs to be entered every time you open a new virtual terminal, which can be inconvenient. You may put this line in your .bashrc or .bash_profile to avoid that repetition. You may also automatically load environments when entering specific directories with tools like direnv.

  2. You can install IOData into your ${HOME} directory, without creating a virtual environment.

    # Install the stable release in your home directory.
    pip3 install qc-iodata
    # alternative: python3 -m pip install qc-iodata

    This is by far the simplest method, ideal to get started, but you have only one home directory. If the installation breaks due to some experimentation, it is harder to make a clean start in comparison to the virtual environment, which you can simply delete.

In case the pip3 executable is not found, pip may be installed in a directory which is not included in your ${PATH} variable. This seems to be a common issue on macOS. A simple workaround is to replace pip3 by python3 -m pip.

In case Python and your operating system are up to date, you may also use pip instead of pip3 or python instead of python3. The 3 is only used to avoid potential confusion with Python 2. Note that the 3 is only present in names of executables, not names of Python modules.

Latest Git revision

This section shows how one can install the latest revision of IOData from the git repository. This kind of installation comes with some risks (sudden API changes, bugs, …) and so be prepared to accept them when using the following installation instructions.

There are two installation methods:

  1. Quick and dirty. Of this method, there are two variants, depending on the correctness of your PATH variable. These different scenarios are explained in more detail in the previous section.

    # correct PATH
    pip install git+
    # broken PATH
    python3 -m pip install git+
  2. Slow and smart. In addition to the two variations in the quick and dirty method, the slow and smart can be useful when you plan to tinker with the source code. You also have the options to use SSH or HTTPS protocols to clone the git repository. Pick whichever works best for you.

    # A) Clone git repo with https OR ssh:
    # The second one only works if you have ssh set up for Github
    #  A1) https
    git clone
    #  A2) ssh
    git clone
    # B) Actual install, 2 different methods.
    #  B1) correct PATH
    pip3 install .
    #  B2) broken PATH
    python3 -m pip install .


The tests are automatically run after each change in the main branch on GitHub, but you may try them again on your own machine after installation. For this to work, you also need to install the development dependencies, as shown below.

# Install pytest
pip3 install qc-iodata[dev]

# Finally, run the tests.
pytest --pyargs iodata -n auto