Implement to_icechunk(region=...)

[vladidobro]

• Closes Build virtual Zarr store using Xarray's dataset.to_zarr(region="...") model #308
• Tests added
• Tests passing
• Full type hint coverage
• Changes are documented in docs/releases.rst
• New functionality has documentation

[codecov]

Codecov Report

❌ Patch coverage is 94.73684% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 89.04%. Comparing base (bf0cb35) to head (30b2ee9).
⚠️ Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
virtualizarr/writers/icechunk.py	94.59%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #873      +/-   ##
==========================================
+ Coverage   89.00%   89.04%   +0.03%     
==========================================
  Files          34       34              
  Lines        1956     1980      +24     
==========================================
+ Hits         1741     1763      +22     
- Misses        215      217       +2     

Files with missing lines	Coverage Δ
virtualizarr/accessor.py	95.65% <100.00%> (+0.04%)	⬆️
virtualizarr/manifests/utils.py	90.74% <ø> (ø)
virtualizarr/writers/icechunk.py	92.12% <94.59%> (-0.14%)	⬇️

... and 1 file with indirect coverage changes

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[vladidobro]

Code coverage: 29 Missing ⚠️

this doesn't look right

EDIT: Ok I see it is because of the failed test probably

[aaron-kaplan]

I notice that this references "private" attributes of a class that's not from this package. Is that considered ok in VirtualiZarr?

[vladidobro]

Hi,
in the referenced issue,
#308 (comment)

@TomNicholas said

Whether or not we vendor xarray kind of depends on how much of xarray we would have to vendor... Some of the internals are more stable than others. I would start out by not vendoring anything and we'll see how fragile that looks.

[TomNicholas]

Yeah it's not "okay", but arguably the lesser of two evils. VirtualiZarr as a whole is a slightly weird re-purposing of xarray.

If this is the only internal import from xarray then we have done better than I expected for this feature.

[TomNicholas]

This is looking good @vladidobro !

[aaron-kaplan]

[Edited: please ignore. The bug turned out to be in my test harness. Writes outside the region of the array do in fact raise an exception.]

[vladidobro]

should I leave this test here? turns out I was unable write a datatree with xarray anyway

[vladidobro]

Hi,
I think the PR is ready, what do you think about it?
Do you have some more ideas for useful tests that I should add?
@aaron-kaplan @TomNicholas @norlandrhagen

EDIT: actually let me just fix mypy, but otherwise I think it's ok