Initial implementation of EUMETSAT IASI-NG reader

[roche-emmanuel]

This PR introduces the initial implementation of the IASI-NG reader for Satpy.

The changes provided here are self-contained in three files:

• satpy/readers/iasi_ng_l2_nc.py: The implementation file for the reader.
• satpy/etc/readers/iasi_ng_l2_nc.yaml: The YAML configuration file for the reader.
• satpy/tests/reader_tests/test_iasi_ng_l2_nc.py: The unit tests for the reader.

There are still a few points I need to address (this list may be extended progressively):

• Check support for products with two-letter names (O3_ and CO_), as I don't think they will pass the current file pattern.
• Confirm with the EUMETSAT team whether the processing logic needs to be adjusted (awaiting clarification on some points concerning the product file specs).
• Extend the unit tests to perform more comprehensive checks on different products (currently only testing with TWV).
• Clean the code and remove debug outputs (e.g., print(...) statements).
• Clarify what needs to be done/added concerning the documentation of this reader.
• Add my name to the AUTHORS.md file.

The idea here is to start this PR early in the development phase to get early feedback and review notes from you, ensuring we are on the right track for eventual PR acceptance.

If you have any feedback on this PR already, please let me know 😊! In the meantime, I will continue working on the points mentioned above and will provide additional details on the changes as they are made on the feature branch.

Thanks for your help 🙏!

[roche-emmanuel]

Alright, so I see from the workflows above that there are some failures due to the formatting of the file, I should maybe start with this before moving forward with the remaining code changes 😉.

[codecov]

Codecov Report

Attention: Patch coverage is 98.42209% with 8 lines in your changes missing coverage. Please review.

Project coverage is 96.12%. Comparing base (0589f61) to head (3089b8d).
Report is 16 commits behind head on main.

Files with missing lines	Patch %	Lines
satpy/readers/iasi_ng_l2_nc.py	96.65%	7 Missing ⚠️
satpy/tests/reader_tests/test_iasi_ng_l2_nc.py	99.66%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2879      +/-   ##
==========================================
+ Coverage   96.10%   96.12%   +0.02%     
==========================================
  Files         377      379       +2     
  Lines       55162    55669     +507     
==========================================
+ Hits        53012    53511     +499     
- Misses       2150     2158       +8     

Flag	Coverage Δ
behaviourtests	3.90% <0.00%> (-0.04%)	⬇️
unittests	96.21% <98.42%> (+0.02%)	⬆️

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[coveralls]

Pull Request Test Coverage Report for Build 12195051508

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
• To avoid this issue with future PRs, see these Recommended CI Configurations.
• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 501 of 509 (98.43%) changed or added relevant lines in 2 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.02%) to 96.228%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
satpy/tests/reader_tests/test_iasi_ng_l2_nc.py	298	299	99.67%
satpy/readers/iasi_ng_l2_nc.py	203	210	96.67%

Totals
Change from base Build 12165642437:	0.02%
Covered Lines:	53757
Relevant Lines:	55864

---

💛 - Coveralls

[roche-emmanuel]

Hi everyone,

We now think that this MR is ready for a review by the Satpy team, so please let me know if you have any feedback on it. Thanks 😉!

[roche-emmanuel]

Bump :-)!

Hi @djhoese , @mraspaud ,

I haven't heard back from you concerning this MR. So I was just wondering if there was anything else I could do on my side to help getting this one into the "processing pipeline" ? Please let me know if you have anything to suggest ;-)

Thanks! 🙏

[mraspaud]

ok I started reviewing this, and it looks sensible, but got distracted by all the comments, so I think we need to address this first.
So let’s start by reading this: https://santim0ren0.medium.com/clean-code-comments-f9eac4ada16d

In this PR I can see different types of comments:

• comments on what the next line is: if the name of the variable or function is good enough, they are not needed
• comments that explain what the following lines do: these lines should then be refactored into a function with a clear name
• comments that complement the docstrings: these should be integrated to the said docstrings

I’m happy to answer any questions if you need help with this :)

[mraspaud]

that comment here surely means this code bit should be in its own function called eg prepare_description_for_variable?

[roche-emmanuel]

Hi @mraspaud ,

Thank you very much for this initial feedback 😊

I've read the article you mentioned, and even if I don't fully agree to this perspective on code comments I think I see your point, and will start working on the requested changes asap. I'll let you when all the fixes are integrated and you can have another look at this PR.

Thanks 🙏!

[roche-emmanuel]

Hello @mraspaud ,

I have now updated the content of the iasi_ng_l2_nc.py file removing those excessive comments (just keeping a couple of "dev notes" in the end).

Now, just to be sure before continuing: you would also expect me to do the same for the test_iasi_ng_l2_nc.py file, right :-)?

Also, I'm not sure if you would expect me to "resolve" each of the points reported above myself, or if you prefer to review the changes first and then resolve those points yourself when you juge the result acceptable (please just let me know if you think I should do it myself).

Thanks!

[mraspaud]

Thanks a lot, looks much better now!
yes it would be great if you could do the same in the test file.
Regarding the resolution of comments, I like it when the original commenter (in this case me) clicks the resolve button.

[roche-emmanuel]

Okay 👌copy that: so I'm updating the test file now.

[roche-emmanuel]

Hi @mraspaud ,

I have now also updated the test_iasi_ng_l2_nc.py file as discussed above. So please let me know when you find some time to give this PR another look, if you notice anything else that we should discuss/change.

Thanks in advance for your time on this 🙏!