def treeOffsets(basePath, snapNum, id, treeName):
""" Handle offset loading for a SubLink merger tree cutout. """
# old or new format
if 'fof_subhalo' in gcPath(basePath, snapNum):
# load groupcat chunk offsets from separate 'offsets_nnn.hdf5' files
with h5py.File(offsetPath(basePath, snapNum), 'r') as f:
groupFileOffsets = f['FileOffsets/Subhalo'][()]
offsetFile = offsetPath(basePath, snapNum)
prefix = 'Subhalo/' + treeName + '/'
groupOffset = id
else:
# load groupcat chunk offsets from header of first file
with h5py.File(gcPath(basePath, snapNum), 'r') as f:
groupFileOffsets = f['Header'].attrs['FileOffsets_Subhalo']
# calculate target groups file chunk which contains this id
groupFileOffsets = int(id) - groupFileOffsets
fileNum = np.max(np.where(groupFileOffsets >= 0))
groupOffset = groupFileOffsets[fileNum]
offsetFile = gcPath(basePath, snapNum, fileNum)
prefix = 'Offsets/Subhalo_Sublink'
with h5py.File(offsetFile, 'r') as f:
# load the merger tree offsets of this subgroup
RowNum = f[prefix + 'RowNum'][groupOffset]
LastProgID = f[prefix + 'LastProgenitorID'][groupOffset]
SubhaloID = f[prefix + 'SubhaloID'][groupOffset]
return RowNum, LastProgID, SubhaloID
def treeOffsets(basePath, snapNum, id):
""" Handle offset loading for a LHaloTree merger tree cutout. """
# load groupcat chunk offsets from header of first file (old or new format)
if 'fof_subhalo' in gcPath(basePath, snapNum):
# load groupcat chunk offsets from separate 'offsets_nnn.hdf5' files
with h5py.File(offsetPath(basePath, snapNum), 'r') as f:
groupFileOffsets = f['FileOffsets/Subhalo'][()]
offsetFile = offsetPath(basePath, snapNum)
prefix = 'Subhalo/LHaloTree/'
groupOffset = id
else:
# load groupcat chunk offsets from header of first file
with h5py.File(gcPath(basePath, snapNum), 'r') as f:
groupFileOffsets = f['Header'].attrs['FileOffsets_Subhalo']
# calculate target groups file chunk which contains this id
groupFileOffsets = int(id) - groupFileOffsets
fileNum = np.max(np.where(groupFileOffsets >= 0))
groupOffset = groupFileOffsets[fileNum]
offsetFile = gcPath(basePath, snapNum, fileNum)
prefix = 'Offsets/Subhalo_LHaloTree'
with h5py.File(offsetFile, 'r') as f:
# load the merger tree offsets of this subgroup
TreeFile = f[prefix+'File'][groupOffset]
TreeIndex = f[prefix+'Index'][groupOffset]
TreeNum = f[prefix+'Num'][groupOffset]
return TreeFile, TreeIndex, TreeNum
def getSnapOffsets(basePath, snapNum, id, type):
""" Compute offsets within snapshot for a particular group/subgroup. """
r = {}
# old or new format
if 'fof_subhalo' in gcPath(basePath, snapNum):
# use separate 'offsets_nnn.hdf5' files
with h5py.File(offsetPath(basePath, snapNum), 'r') as f:
groupFileOffsets = f['FileOffsets/' + type][()]
r['snapOffsets'] = np.transpose(
f['FileOffsets/SnapByType'][()]) # consistency
else:
# load groupcat chunk offsets from header of first file
with h5py.File(gcPath(basePath, snapNum), 'r') as f:
groupFileOffsets = f['Header'].attrs['FileOffsets_' + type]
r['snapOffsets'] = f['Header'].attrs['FileOffsets_Snap']
# calculate target groups file chunk which contains this id
groupFileOffsets = int(id) - groupFileOffsets
fileNum = np.max(np.where(groupFileOffsets >= 0))
groupOffset = groupFileOffsets[fileNum]
# load the length (by type) of this group/subgroup from the group catalog
with h5py.File(gcPath(basePath, snapNum, fileNum), 'r') as f:
r['lenType'] = f[type][type + 'LenType'][groupOffset, :]
# old or new format: load the offset (by type) of this group/subgroup within the snapshot
if 'fof_subhalo' in gcPath(basePath, snapNum):
with h5py.File(offsetPath(basePath, snapNum), 'r') as f:
r['offsetType'] = f[type + '/SnapByType'][id, :]
else:
with h5py.File(gcPath(basePath, snapNum, fileNum), 'r') as f:
r['offsetType'] = f['Offsets'][type +
'_SnapByType'][groupOffset, :]
return r