[ENH] Read Rockstar members

[cphyc]

PR Summary

This allow to read member data from Rockstar catalogues.

PR Checklist

• Adds a test for any bugs fixed. Adds tests for new features.

[neutrinoceros]

@yt-fido test this please

[neutrinoceros]

@cphyc I think adjustments are needed to pass the new test

[brittonsmith]

I'm really glad someone finally had the courage to implement this. Can you also add a section in the Rockstar frontend docs in doc/source/examining/loading_data.rst?

[brittonsmith]

I'm not sure where the conflicts came from, but the rest looked good to me. If they can be cleared up, I think this is ready to be merged.

[neutrinoceros]

@cphyc conflicts probably came from #4275
Happy to merge this once they're resolved

[neutrinoceros]

@yt-fido test this please

[neutrinoceros]

@yt-fido test this please

[neutrinoceros]

We have one failing test to deal with

[brittonsmith]

I cannot reproduce the failing test locally with a Python 3.10 install. Is there a way to get more information?

[cphyc]

I think this might be real. I need to investigate!

Weird; I have tried locally and cannot reproduce the error on 3.9, 3.10 or 3.11.

Here's the code I tried

import yt

ds = yt.load_sample("rockstar_halos/halos_0.0.bin")

for halo_id, Npart in zip(
    ds.r["halos", "particle_identifier"],
    ds.r["halos", "num_p"],
):
    print(halo_id)
    halo = ds.halo("halos", halo_id)
    assert halo is not None

    # Try accessing properties
    halo.position
    halo.velocity
    halo.mass

    # Make sure we can access the member particles
    assert len(halo.member_ids) == Npart

This should be the code of the failing test, unless I am mistaken.

[cphyc]

@yt-fido test this please.

[neutrinoceros]

@cphyc the test server is dead, see discussion on Slack.

[neutrinoceros]

@yt-fido Test this please

[cphyc]

I made a bit of progress - it seems that the checksum of the data is not the same on fido as it is on my computer:

# locally
/home/…/rockstar_halos/halos_0.0.bin has sha256sum b'09accfb7ab6f162f29fcfb7c6393e207ba1be9d61cbdc230f17d39f0e90914d7'
/home/…/rockstar_halos/halos_0.1.bin has sha256sum b'42e64f974f7d72f201443d42463fd642f8e37c7c485eac54810e3be8adfd0a22'
# on yt-fido
/mnt/yt/rockstar_halos/halos_0.0.bin has sha256sum b'd4c395708e153ae9ec32873c1b1b13f52ee5e829b6cee34e2ab91c67fe8bdf20'
/mnt/yt/rockstar_halos/halos_0.1.bin has sha256sum b'42e64f974f7d72f201443d42463fd642f8e37c7c485eac54810e3be8adfd0a22'

I should note that the local data was downloaded through yt.load_sample, so it should reflect whatever is on https://yt-project.org/data/.
@Xarthisius do you have an idea what's happening?

[cphyc]

I am quite confident is that the test data isn't the same as the one online. @Xarthisius would it be possible to make sure that the dataset on jenkins is the same as the one obtained when using load_sample("rockstar_halos/halos_0.0.bin")?

I have tested locally and it works like a charm.

[cphyc]

@yt-fido Test this please

[neutrinoceros]

adding the "enhancement" label just to make Mergeable Bot happy

[cphyc]

@neutrinoceros @brittonsmith I think the "Mergeable" bot is stuck, unless I am misunderstanding?

[neutrinoceros]

Removing and re-adding a label did the trick.

[matthewturk]

Not an f-string?

[cphyc]

Not anymore :)