ENH: Adding Cholla Frontend

[chummels]

This adds a frontend to yt for working with datasets from the CHOLLA code (https://github.com/cholla-hydro/cholla). It replaces the previous attempt at this from a few years ago (PR #1944 )

CHOLLA is a super straightforward code format: it's a fixed-resolution grid code saved to HDF5 files with attributes storing simulation parameters. For simplicity, I've also made it so nprocs=1, so it reads a single grid for the whole dataset, since it's unigrid. After I get this working, I'll make yt chunk it into smaller-sized chunks for for efficiency. But for now, I just want something that works.

The frontend works so far for basic things like reporting fields and parameters and such. But when one attempts to actually make a slice or something, it fails with a Arrays are not of correct shape error. The main remaining hurdles are getting the _read_fluid_selection() and _read_chunk_data() functions working in io.py.

Any assistance in finishing up this frontend would be greatly appreciated. The CHOLLA code author, @evaneschneider, and her students are interested in contributing to active development in yt when they can actually get their code to be read in successfully.

For testing purposes, a 1-zone CHOLLA test dataset can be found here: http://chummels.org/cholla/1.h5 .

[chummels]

I added some basic tests which just ensure that the test file is recognized as a CHOLLA dataset, that it can load it, and that it has the fields that are expected and can access them. Are there any other canonical tests that are used to test out frontends or is this enough for now?

[matthewturk]

Looks like this is nearly done -- are we waiting for answer tests? Is that something someone else could help out with?

[matthewturk]

pre-commit.ci autofix

[chummels]

Yeah, I've been slow on this front, as I'm at some conferences in Switzerland for a couple of weeks. If we want answer tests, I can potentially get to this, but it won't be until I get back. But if someone else wanted to craft a basic answer test, by all means go for it.

[neutrinoceros]

If we're not able to finish this in the next couple weeks I'd suggest leaving it to yt 4.2 which - the way I envision it - should happen much closer in time than 4.1 is to 4.0

[matthewturk]

@neutrinoceros I think we need to hold 4.1 until this is in, and I will work on this concurrently with finishing up #3421 . @chummels can you enumerate what is required still, and I can take it on?

[jzuhone]

I agree, this should go in 4.1

[chummels]

@matthewturk I think all that remains to be done for this PR is the addition of an answer test or two using the dataset that is already being used in the tests. It's a super simple dataset with a density gradient across the grids, so I guess just make a ProjectionPlot and SlicePlot and PhasePlot answer test and then call it a day? I am not sure, but that seems like it should be sufficient?

[matthewturk]

I've gone ahead and added some simple tests. These work locally, but it's hard for me know if I did everything properly, so I guess we'll see what fido says.

[neutrinoceros]

close/open to refresh CI now that unrelated failures are resolved on main

[neutrinoceros]

It seems that the new tests break pytest. I think there is a precedent for this and you could simply ignore the new test module on pytest with this patch:

diff --git a/pyproject.toml b/pyproject.toml
index 6306dea36..9b80ade02 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -67,6 +67,7 @@ addopts = '''
     --ignore-glob='*_nose.py'
     --ignore='yt/frontends/owls_subfind/tests/test_outputs.py'
     --ignore='yt/frontends/ramses/tests/test_outputs.py'
+    --ignore='yt/frontends/cholla/tests/test_outputs.py'
 '''

[neutrinoceros]

FTR I just merged from main, but I really meant to do this for #3421. This should not cause any trouble other than wasting CI time. Sorry folks

[neutrinoceros]

I don't have any blocking comments left. I believe Matt should be able to merge this even as a co-author.