TreeFarm.trace_ancestors(halo_type, root_ids, fields=None, filename=None)

Trace the ancestry of a given set of halos.

A merger-tree for a specific set of halos will be created, starting with the last halo catalog and moving backward.

halo_type : string
The type of halo, typically “FOF” for FoF groups or “Subfind” for subhalos.
root_ids : integer or array of integers
The halo IDs from the last halo catalog for the targeted halos.
fields : optional, list of strings
List of additional fields to be saved to halo catalogs.
filename : optional, string
Directory in which merger-tree catalogs will be saved.