def getHaloData(whichHalo, simulation='Illustris-1', snapshot=135):
"""
Returns a dictionary with all catalog data corresponding to a halo or subhalo
Docstring is identical for `getHaloData`and `getSubhaloData`
These two commands are effectively identical. They have the same input and
output, except one deals with halos (roughly speaking 'groups/ clusters')
and the other with the subhalos in those halos (the 'galaxies' in those
'groups'). See Intro to the Data (or Naming Conventions) for more on the
data structure/ naming conventions used.
Parameters
----------
whichHalo : int
halo/subhalo number of the galaxy you wish to get data for
simulation : str
Which simulation to pull data from
snapshot : int
Which snapshot (moment in time) to pull data from
Returns
-------
data : dict
A dictionary of data, with an entry for each field (with field names
from section 2. of this page
http://www.illustris-project.org/data/docs/specifications/
"""
units = changeUnits.makeHaloDict(simulation=simulation, snapshot=snapshot)
url = 'http://www.illustris-project.org/api/' + simulation + '/snapshots/' + str(
snapshot) + '/halos/' + str(whichHalo) + '/info.json'
data = get(url)
haloData = data['Group']
haloKeys = list(haloData.keys())
for i in range(len(haloKeys)):
oldValue = np.array(haloData[haloKeys[i]])
convFactor = units[haloKeys[i]]
haloData[haloKeys[i]] = convFactor * oldValue
return haloData
def getHaloField(field,
simulation='Illustris-1',
snapshot=135,
fileName='tempCat',
rewriteFile=1):
"""
Data from one field for all halos/subhalos in a given snapshot
These two commands are near identical, so I'm going to detail them both here.
They have the same input and output, except one deals with halos (roughly
speaking 'groups/ clusters') and the other with the subhalos in those halos
(the 'galaxies' in those 'groups'). See Intro to the Data (or Naming
Conventions) for more on the data structure/ naming conventions used.
Parameters
----------
field : str
Name of the one field to be returned. The fields can be found in
section 2. of this page
http://www.illustris-project.org/data/docs/specifications/
simulation : str
Which simulation to pull data from
snapshot : int
Which snapshot (moment in time) to pull data from
The following two parameters are discussed in more detail here!
fileName : str
Default is 'tempGal.hdf5'. Filename for where to store or load the data
rewriteFile : int
[0 or 1] If this is equal to 0 then the program will try and pull data
from the file specified by fileName rather than re-downloading. This can
save time, especially for galaxies which are large or you will work on
frequently, but you will only be able to access fields you originally
requested
Returns
-------
data : array
A numpy array containing the data for a specific field for all halos/subhalos
Examples
--------
Let's pull out the velocity dispersion of stars in every subhalo and their
DM mass, and then restrict ourselves to only looking at the primary subhalo
in each halo (i.e. the most massive galaxy in each group).
The velocity dispersion (N_sub values)
>>> galaxyVelDisp=iApi.getSubhaloField('SubhaloVelDisp')
The mass of each different particle type in a galaxy (N_sub x 6 values,
see getGalaxyData for more info on particle types)
>>> galaxyMassType=iApi.getSubhaloField('SubhaloMassType')
The subhalo number of the primary subhalo in each halo (N_halo values)
>>> primarySubhalos=iApi.getHaloField('GroupFirstSub')
Velocity dispersion of primary subhalos
>>> velDisp=galaxyVelDisp[primarySubhalos]
Total dark matter mass of primary subhalos
>>> mDM=galaxyMassType[primarySubhalos,1]
"""
if rewriteFile == 1: # redownloads file from the internet
url = 'http://www.illustris-project.org/api/' + simulation + '/files/groupcat-' + str(
snapshot) + '/?Group=' + field
dataFile = get(url, fName=fileName)
if rewriteFile == 0: # if we're not redownloading need to set path to the file
dataFile = fileName + '.hdf5'
with h5py.File(dataFile, 'r') as f:
data = np.array(f['Group'][field])
units = changeUnits.makeHaloDict(simulation=simulation, snapshot=snapshot)
return data * units[field]