Load halo from snapshot

Carter Rhea
  • 1
  • 24 Jun '20

I am trying to obtain halo information for certain halos in the Illustris-3 simulations.

I have downloaded the snapshot information for z=0 locally and am using the following command to query the gas data:
il.snapshot.loadHalo(basePath,135, 16937, 'gas')

However, I receive the following error:

Unable to open file (unable to open file: name = '/home/carterrhea/Documents/Illustris/output/../postprocessing/offsets/offsets_135.hdf5', errno = 2, error message = 'No such file or directory', flags = 0, o_flags = 0)

I can't find where/how to download the offsets. Could you provide some guidance in this?

Thank you,
Carter Rhea

Dylan Nelson
  • 1
  • 26 Jun '20

Hi Carter,

For the original Illustris simulation, the offsets are inside the group catalog files, so you shouldn't need to download them separately.

Do you have the two files here:


this is the entirety of the group catalog for Illustris-3 at z=0. Then you can type e.g.

$ h5ls -r groups_135.0.hdf5

/                        Group
/Group                   Group
/Group/GroupBHMass       Dataset {65863}
/Header                  Group
/Offsets                 Group
/Offsets/Group_FuzzByType Dataset {65863, 6}
/Offsets/Group_SnapByType Dataset {65863, 6}
/Offsets/Subhalo_LHaloTreeFile Dataset {60604}
/Offsets/Subhalo_LHaloTreeIndex Dataset {60604}
/Offsets/Subhalo_LHaloTreeNum Dataset {60604}
/Offsets/Subhalo_SnapByType Dataset {60604, 6}
/Offsets/Subhalo_SublinkLastProgenitorID Dataset {60604}
/Offsets/Subhalo_SublinkRowNum Dataset {60604}
/Offsets/Subhalo_SublinkSubhaloID Dataset {60604}
/Subhalo                 Group

is this what you see?

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