py-galaxies is a semi-analytic galaxy formation model within the L-Galaxies family: https://lgalaxiespublicrelease.github.io.

It features 3 major developments:

• A python front-end to make parameter selection and I/O much easier.
• The use of merger trees rather than a merger graph, to allow splitting of halos and subhalos.
• The formation of galaxies within subhalos, rather than halos, and the replacement of "Type 0" galaxies with galaxies within central subhalos, which are not guaranteed to exist, for example in merging systems.

For usage instructions and full documentaion, see https://py-galaxies.readthedocs.io/en/latest/