def trace_descendents(self, halo_type, fields=None, filename=None):
"""
Trace the descendents of all halos.
A merger-tree for all halos will be created, starting
with the first halo catalog and moving forward.
Parameters
----------
halo_type : string
The type of halo, typically "FOF" for FoF groups or
"Subfind" for subhalos.
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.
"""
output_dir = os.path.dirname(filename)
if self.comm.rank == 0 and len(output_dir) > 0:
ensure_dir(output_dir)
all_outputs = self.ts.outputs[:]
ds1 = ds2 = None
for i, fn2 in enumerate(all_outputs[1:]):
fn1 = all_outputs[i]
target_filename = get_output_filename(
filename, "%s.%d" % (_get_tree_basename(fn1), 0), ".h5")
catalog_filename = get_output_filename(
filename, "%s.%d" % (_get_tree_basename(fn2), 0), ".h5")
if os.path.exists(target_filename):
continue
if ds1 is None:
ds1 = self._load_ds(fn1, index_ptype=halo_type)
ds2 = self._load_ds(fn2, index_ptype=halo_type)
if self.comm.rank == 0:
_print_link_info(ds1, ds2)
target_halos = []
if ds1.index.particle_count[halo_type] == 0:
self._save_catalog(filename, ds1, target_halos, fields)
ds1 = ds2
continue
target_ids = \
ds1.r[halo_type, "particle_identifier"].d.astype(np.int64)
njobs = min(self.comm.size, target_ids.size)
pbar = get_pbar("Linking halos", target_ids.size, parallel=True)
my_i = 0
for halo_id in parallel_objects(target_ids, njobs=njobs):
my_halo = ds1.halo(halo_type, halo_id)
target_halos.append(my_halo)
self._find_descendent(my_halo, ds2)
my_i += njobs
pbar.update(my_i)
pbar.finish()
self._save_catalog(filename, ds1, target_halos, fields)
ds1 = ds2
clear_id_cache()
if os.path.exists(catalog_filename):
return
if ds2 is None:
ds2 = self._load_ds(fn2, index_ptype=halo_type)
if self.comm.rank == 0:
self._save_catalog(filename, ds2, halo_type, fields)
def trace_ancestors(self, 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.
Parameters
----------
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.
"""
output_dir = os.path.dirname(filename)
if self.comm.rank == 0 and len(output_dir) > 0:
ensure_dir(output_dir)
all_outputs = self.ts.outputs[::-1]
ds1 = None
for i, fn2 in enumerate(all_outputs[1:]):
fn1 = all_outputs[i]
target_filename = get_output_filename(
filename, "%s.%d" % (_get_tree_basename(fn1), 0), ".h5")
catalog_filename = get_output_filename(
filename, "%s.%d" % (_get_tree_basename(fn2), 0), ".h5")
if os.path.exists(catalog_filename):
continue
if ds1 is None:
ds1 = self._load_ds(fn1, index_ptype=halo_type)
ds2 = self._load_ds(fn2, index_ptype=halo_type)
if self.comm.rank == 0:
_print_link_info(ds1, ds2)
if ds2.index.particle_count[halo_type] == 0:
mylog.info("%s has no halos of type %s, ending." %
(ds2, halo_type))
break
if i == 0:
target_ids = root_ids
if not iterable(target_ids):
target_ids = np.array([target_ids])
if isinstance(target_ids, YTArray):
target_ids = target_ids.d
if target_ids.dtype != np.int64:
target_ids = target_ids.astype(np.int64)
else:
mylog.info("Loading target ids from %s.", target_filename)
ds_target = yt_load(target_filename)
target_ids = \
ds_target.r["halos",
"particle_identifier"].d.astype(np.int64)
del ds_target
id_store = []
target_halos = []
ancestor_halos = []
njobs = min(self.comm.size, target_ids.size)
pbar = get_pbar("Linking halos", target_ids.size, parallel=True)
my_i = 0
for halo_id in parallel_objects(target_ids, njobs=njobs):
my_halo = ds1.halo(halo_type, halo_id)
target_halos.append(my_halo)
my_ancestors = self._find_ancestors(my_halo,
ds2,
id_store=id_store)
ancestor_halos.extend(my_ancestors)
my_i += njobs
pbar.update(my_i)
pbar.finish()
if i == 0:
for halo in target_halos:
halo.descendent_identifier = -1
self._save_catalog(filename, ds1, target_halos, fields)
self._save_catalog(filename, ds2, ancestor_halos, fields)
if len(ancestor_halos) == 0:
break
ds1 = ds2
clear_id_cache()