Configuration Options

This page documents the configuration options used by CTree.

General notes:

• Lines starting with # are treated as comments.

• Whitespace around = is ignored.

I/O related

Option	Format	Default	Description
out_dir	string	(required)	Path for the output data. The output data are ctree_tree.dat and ctree_key.dat ctree_tree.dat has the Lagrangian branch data for the entire branches. ctree_key.dat gives the mapping for (#Snap, #ID)->(branch index). The data format is explaned in Tree Key File Format. The output data can be post-processed with example codes in ./example/rdtree.py or ./example/rdtree.pro Examples how to load a branch data is given in Reading example.
iotype	string	(required)	Catalog type. Currently (as of Feb 2026), the following options are available. VR (VELOCIraptor in ascii format) VELUGA (VELOCIraptor post-processed data using https://github.com/JinsuRhee/VELUGA) HM (HaloMaker catalogs)
vr_dir_catalog	string	(required)	Path for the catalog data when iotype = VR CTree searches raw VELOCIraptor outputs (e.g., *.catalog.dat0) in directories divided by snapshot numbers (e.g.,) vr_dir_catalog/vr_dir_catalog_prefix SSSS vr_dir_catalog_suffix/
vr_dir_catalog_prefix	string
vr_dir_catalog_suffix	string
vr_dir_catalog_snapdigit	integer	4	The digit number for snapshot number in the directory name (the default value is 4)
veluga_dir_catalog	string	(required)	Path for the catalog data when iotype = VELUGA Path at which snap_* directories are located horg option should be given
hm_dir_catalog	string	(required)	Path for the catalog data when iotype = HM Path at which *.bricks are located
loadtree	Y or N	(required)	Flag whether a pre-existing merger tree is used If set, CTree begins with the given merger tree data and reparis the branches If set, loadtree_ftree and loadtree_fkey should be given The tree data format is described in Output data format
loadtree_ftree	string	(required)	Path for the merger tree branch data when loadtree = Y
loadtree_fkey	string	(required)	Path for the merger tree key data when loadtree = Y
snapi, snapf	integer	(required)	Snapshot range identifers. CTree loops from snapf to snapi A user can also give the snapshot list by a Ascii file with snaplist
snaplist	string		File identifer including the list of snapshots (line-by-line). The list is automatically sorted
horg	h or g	h	Flag for the catalog type (Halo or Galaxy). It is only used when reading the catalog data (iotype = VELUGA and iotype = HM).
makecheck	integer	10	Control saving of intermediate data. For a positive value, data are saved at snapshots where the snapshot number modulo this value equals zero. CTree can be restarted from these snapshots. If a negative value is provided, no intermediate data are saved.
loadcheck	integer	-1	A snapshot number for the restart, if exists.

Branch related parameters

Option	Format	Default	Description
n_search	integer	10	The number of snapshots to be used in progenitor searches It determines the size of list tables of branches where candidate progenitor information is written
meritfrac	float	0.5	Fraction to allow a suboptimal later progenitor to be a branch point CTree first defines the progenitor with the highest merit in the list talbe as the next branch point If a later progenitor with a merit > ctree_merit_frac X (Maximum merit), CTree allows this progenitor to be the next one, mainly to avoid big jumps among the branch points.
core_n	integer	10	The number of snapshots used when extracting core particles. ctree_core_n snapshots with the ctree_core_dn interval are used
core_dn	integer	5	Snapshot interval for the core particle extraction
core_minfrac	float	0.25	Fraction to define core particles. A subset of particles with N occurrances are defined as core particles if their fraction is higher than ctree_meritfrac Otherwise, CTree repeats the core particle searches with a lower occurrance number
meritlimit	float	0.001	The lower limit of the merit for progenitors. If the best progenitor has the lower merit than meritlimit, the connection is not allowed
minbranchlength	integer	5	After all branches are constructed, branches whose length is lower than minbranchlength are removed

Branch Maker

These options are used when building initial branches based on the connectivity information of objects between snapshots.

TreeFrog output is only available at the moment

Option	Format	Default	Description
branchmaker	Y or N	(required)	Flag to turn on/off the branchmaker
brtype	string	(required)	Tree data catalog type TF (TreeFrog)
tfdir	string	(required)	Path where TreeFrog raw outputs (*.tree) are located
treedir	des or prg	des	Branch making direction des : descendants searches prg : progenitors searches