feature: Support writing predictions to extxyz files

[AntObi]

• This closes [FEATURE] Support writing predictions from mtt eval to extxyz files. #1255, which enables predictions from mtt eval to also be written to extxyz files in the same format as the currently supported xyz for any usage where users may prefer the extxyz file format.

Contributor (creator of pull-request) checklist

• Tests updated (for new features and bugfixes)?
• Documentation updated (for new features)?
• Issue referenced (for PRs that solve an issue)?

Maintainer/Reviewer checklist

• CHANGELOG updated with public API or any other important changes?
• GPU tests passed (maintainer comment: "cscs-ci run")?

---

📚 Documentation preview 📚: https://metatrain--1256.org.readthedocs.build/en/1256/

[ceriottm]

to my understanding, .xyz output is ALREADY effectively extxyz (which itself is a non-standard suffix for a non-standard extension of a non-standard format)

[pfebrer]

Yes, this is what we discussed in the issue.

I guess this comes down to: @AntObi, will you use it? :)

I think if there is somebody who thinks their life will be easier then it should not be a problem to have it around and it's worth it, otherwise it's just an unnecessary feature 😅

[pfebrer]

I'm also very happy that external humans contribute, so if you think it's going to be used it's all good for me 👍 I'd rather not start a phylosophical debate on this one haha

[Luthaf]

cscs-ci run

[AntObi]

to my understanding, .xyz output is ALREADY effectively extxyz (which itself is a non-standard suffix for a non-standard extension of a non-standard format)

Yes, this is what we discussed in the issue.

I guess this comes down to: @AntObi, will you use it? :)

I think if there is somebody who thinks their life will be easier then it should not be a problem to have it around and it's worth it, otherwise it's just an unnecessary feature 😅

I'm also very happy that external humans contribute, so if you think it's going to be used it's all good for me 👍 I'd rather not start a phylosophical debate on this one haha

Yep, it's something that I would use. Additionally, it adds a bit of consistency, since Metatrain supports reading both .xyz and .extxyz files,

metatrain/src/metatrain/utils/data/readers/readers.py

Lines 19 to 23 in e2af067

	DEFAULT_READER = {
	".xyz": "ase",
	".extxyz": "ase",
	".mts": "metatensor",
	}

so it should also support both file extensions for writing as well.

[pfebrer]

Thanks!