Installation

The framework is registered on PyPI, it can be installed with the following procedure:

# Create a directory where you're going to write your scripts,
# notebooks, etc.
mkdir -p ~/litebird && cd ~/litebird

# Create a virtual environment with
virtualenv lbs_env
# or with
python3 -m venv lbs_env

# Activate the environment
. lbs_env/bin/activate

# Finally install litebird_sim with pip
pip install litebird_sim

When the command is completed, check that everything works by issuing the following command at the terminal prompt:

python -c "import litebird_sim"

A similar procedure can be used with conda:

# Create a conda environment
conda create -n lbs_env python=3.9

# Activate the environment
conda activate lbs_env

# Finally install litebird_sim with pip
pip install litebird_sim

Hacking litebird_sim

To develop litebird_sim, you can create an enviroment, as described above, then checkout and install a local copy of the framework.

# Create a virtual environment and activate it
virtualenv my_venv && . my_venv/bin/activate

# First clone the code
git clone https://github.com/litebird/litebird_sim litebird_sim

# Then install it with pip
cd litebird_sim && pip install .

Run code validators

As every commit and pull request is validated through ruff, you might want to run them before pushing modifications to the GitHub repository. In this case enter the litebird_sim directory and run the following command:

# Always remember to activate your virtual environment!
. my_venv/bin/activate

# Install some useful hooks for git
pre-commit install

What this command does is to install a few «pre-commit» hooks: they are programs that are run whenever you run git commit and do some basic checks on your code before actually committing it. These checks are the same that are run by GitHub once you push your changes in a pull request, so they can save you several back-and-forth iterations.

Development with MPI

As explained in the chapter Multithreading and MPI, the LiteBIRD Simulation Framework supports MPI. To use it, you must ensure that mpi4py is installed.

If you have created a virtual environment to work with litebird_sim (as you should have), just install it using pip:

pip install mpi4py

That’s it: the next time you run a script that uses litebird_sim, MPI functions will be automatically enabled in the framework. See the chapter Multithreading and MPI for more details.