Enable to pass a custom function to Scene.aggregate

[ghiggi]

This small PR adds the option to pass a custom function to Scene.aggregate

• Closes #xxxx
• Tests added
• Fully documented
• Add your name to AUTHORS.md if not there already

[codecov]

Codecov Report

Merging #2497 (dba604e) into main (3b7a477) will increase coverage by 0.01%.
The diff coverage is 90.47%.

@@            Coverage Diff             @@
##             main    #2497      +/-   ##
==========================================
+ Coverage   94.83%   94.85%   +0.01%     
==========================================
  Files         337      337              
  Lines       49430    49658     +228     
==========================================
+ Hits        46875    47101     +226     
- Misses       2555     2557       +2     

Flag	Coverage Δ
behaviourtests	4.41% <9.52%> (-0.02%)	⬇️
unittests	95.47% <90.47%> (+0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
satpy/scene.py	93.60% <85.71%> (+0.07%)	⬆️
satpy/tests/scene_tests/test_resampling.py	100.00% <100.00%> (ø)

... and 23 files with indirect coverage changes

[coveralls]

Pull Request Test Coverage Report for Build 5346938525

• 19 of 21 (90.48%) changed or added relevant lines in 2 files are covered.
• 100 unchanged lines in 6 files lost coverage.
• Overall coverage increased (+0.008%) to 95.422%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
satpy/scene.py	12	14	85.71%

Files with Coverage Reduction	New Missed Lines	%
satpy/composites/init.py	6	91.24%
satpy/readers/avhrr_l1b_gaclac.py	6	95.68%
satpy/readers/olci_nc.py	11	94.2%
satpy/readers/geocat.py	18	88.82%
satpy/readers/seviri_l1b_native.py	21	86.82%
satpy/readers/nwcsaf_nc.py	38	82.0%

Totals
Change from base Build 5141473420:	0.008%
Covered Lines:	47216
Relevant Lines:	49481

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💛 - Coveralls

[djhoese]

Seems simple enough. I had one small change to request. Otherwise, I'm wondering if you could refactor the aggregate method into smaller sub-methods (or external functions) to make CodeScene happy?

[ghiggi]

Complementary note: this method fails if the source area is a SwathDefinition because the "resolution" can't be inferred if not present as attributes to lons/lats

[ghiggi]

@mraspaud milestone v0.43.0

[mraspaud]

Thanks for adding this! just a couple of comments inline.

[mraspaud]

This feels like it should already be present somewhere in pyresample. I think we have a method called geocentric_resolution, can it be used here?

[ghiggi]

I could do that but it would break the back compatibility !
For AreaDefinition for example, right now (and in the past) the method is/was using pixel_size (in units of projection coordinates). While geocentric_resolution if I understand correctly would provides the geocentric resolution (in degrees)

[djhoese]

You are correct that it is not the same, but I do want to clarify it should be in meters...just not the same meters as the projection. I think, especially since you didn't write this code, that it can stay as is (again, my opinion). I do think the .resolution should be .attrs["resolution"] though. If you have other changes to make maybe you could do that too.

[ghiggi]

@djhoese you mean the Scene DataArray .attrs['resolution']? But is this always updated? Also when resampling to new area/swaths? And what if the attribute is missing? I guess we should discuss this on a separate issue and do a separate PR ...

[djhoese]

No no, sorry. I mean in the except clause it does area.lats.resolution. If I'm understanding this code area is a SwathDefinition in this except block, .lats is a DataArray, and area.lats.resolution is a shortcut to area.lats.attrs["resolution"]. The .attrs form of accessing this information is the preferred way of doing it.

[ghiggi]

Done and likely ready to be merged ;)

[mraspaud]

LGTM