I'm interested in obtain the SubhaloMass of the Subhalos and the SnapNum in Illustris-3, but I've a problem in groupcat I obtain SubhaloMass but not snapnum, the snapnum are in loadtree and SubhaloMass in loadtree not is the same that SubhaloMass in groupcat (i.e. data number in len(groupcat['SubhaloMass']= 121209 and
len(loadtree[' Subhaloass']) is different). How can I obtain SubhaloMass and the related Snapnum?
When you load SubhaloMass group the groupcat, then you must specify the snapshot number to do so. So, then you know it already for those subhalos.
Loading trees, then yes you can request both SubhaloMass and SnapNum, and also SubfindID. If you then use this snapshot number, and load the group catalog at this snapshot, then you should find that the value of the group catalog SubhaloMass at index SubfindID equals the SubhaloMass value from the tree at that SnapNum.
I can only access to 2044
Is the problem 'Warning, empty return. Subhalo [N] at snapNum [N] not in tree.'?
If so, this is simply a possibility, particularly with very small subhalos, who have no progenitors. You should check for this and skip them, since they won't have any formation time.
yes that's the problem, the mass (subhalomass in groups) at 2055 position is 0.174652.
How can I include those with history formation only and avoid this error?
thank you very much