Feature: Add AstroPy Support by cvanelteren · Pull Request #607 · Ultraplot/UltraPlot

cvanelteren · 2026-03-07T22:34:27Z

Closes#606
Issue #606 is that UltraPlot does not correctly handle Astropy WCS projection objects passed as projection=mosaic.wcs.

In practice, this shows up when code like ax.get_transform("icrs") fails with:

TypeError: Artist.get_transform() takes 1 positional argument but 2 were given

The underlying problem is:

UltraPlot was not preserving/wrapping non-string projection objects like WCS during axes creation.
The external-axes container then exposed the wrong get_transform() method, so WCS-specific transform lookups were
masked by the base Matplotlib artist API.

cvanelteren · 2026-03-09T04:48:57Z

Integration requires more effort see #606 -- don't have time to work on this atm.

cvanelteren · 2026-03-12T00:22:58Z

@astrogewgaw can you test this?

astrogewgaw · 2026-03-12T06:05:11Z

@cvanelteren I tested this using the minimal working example I shared earlier (the code for which has been added to the issue now as a comment here; do have a look), and it works! I will see if I can test it with some FITS images as well. Also, maybe @beckermr can also have a look at this if he has some time? Just a thought.

cvanelteren · 2026-03-12T09:56:57Z

Need to do some more testing and quality check the implementation; Astropy seems like a serious undertaking. We should also reach out to add us on the list of packages if this goes through.

cvanelteren · 2026-03-12T09:58:26Z

Key thing is that supporting other axis implementations is that it will become harder for me to keep up if the backend changes on their end; if we keep this in house and it changes significantly this would require me to keep up-to-date with their changes. Since I am not an astro-person, this would be harder to catch than users that use it every day. Naturally, I can write tests but this will not be perfect.

astrogewgaw · 2026-03-13T07:04:44Z

@cvanelteren Makes sense. I can help with some of the testing, but I don't deal with that many astronomical images in my line of work, I am more of a time-domain astronomy guy. Do let me know if and when this makes to a future release of UltraPlot; until then, I can point my package to the latest commit on the main branch.

cvanelteren · 2026-03-19T02:45:09Z

Putting this on the back burner as it is nicer to add this after a refactor happens on figure.py that will design contracts as to how we interface with other axes in clean way so I don't have to repeat my steps.

cvanelteren · 2026-07-21T06:24:21Z

This needs review preferably from someone in the field -- otherwise it is ready to go.

Closes#606

Route Astropy WCS projections through a native AstroAxes bridge instead of the external container, preserve per-axes transform dispatch for SubplotGrid, and keep shared panel labels stable for both cartesian and astro axes.

Move logical ticklabel state access into the axes classes so Figure can share and hand off panel labels without branching on cartesian, geo, and astro subplot types.

Make the Astropy WCS bridge a true optional import by loading and registering AstroAxes only on WCS-specific access, while keeping the panel/share refactors and import behavior covered by tests.

Make Astropy a true opt-in runtime extra by adding dedicated package extras for Astro, geographic, and ternary integrations, along with an all extra that installs the optional runtime stack without changing the default UltraPlot dependency set. At the same time, tighten the Astro axes import path so explicit WCS usage fails with a clear installation message instead of silently returning None. astro.py is now treated as an Astropy-backed module again, the lazy loader in axes.__init__ raises a targeted ImportError with the recommended install command, and WCS string resolution in projections.py now relies on that explicit failure path. This also expands inline documentation in AstroAxes to make the WCS override points clearer, and updates the import tests to match the new optional-dependency behavior.

Add a dedicated Astropy WCS section to docs/usage.rst so the new AstroAxes integration is discoverable from the main usage guide. The section explains the optional install path, shows the two supported creation patterns (direct WCS objects and the "wcs" alias), and clarifies that UltraPlot handles figure-level sharing/layout while advanced coordinate customization still lives on ax.coords[...].

Revert the non-sharing left and bottom panel relabeling that shifted shared subplot labels and broke existing image baselines. Also harden the Astro lazy-import test so missing astropy does not crash the subprocess before the optional import path is exercised.

codecov · 2026-08-13T05:03:44Z

Codecov Report

❌ Patch coverage is 43.64964% with 386 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
ultraplot/axes/astro.py	0.00%	202 Missing ⚠️
ultraplot/tests/test_astro_axes.py	4.83%	118 Missing ⚠️
ultraplot/axes/__init__.py	43.90%	19 Missing and 4 partials ⚠️
ultraplot/internals/projections.py	83.82%	15 Missing and 7 partials ⚠️
ultraplot/figure.py	79.24%	7 Missing and 4 partials ⚠️
ultraplot/axes/container.py	57.14%	1 Missing and 2 partials ⚠️
ultraplot/tests/test_imports.py	75.00%	2 Missing and 1 partial ⚠️
ultraplot/axes/base.py	80.00%	1 Missing and 1 partial ⚠️
ultraplot/gridspec.py	83.33%	1 Missing and 1 partial ⚠️

📢 Thoughts on this report? Let us know!

cvanelteren mentioned this pull request Mar 7, 2026
Feature request: Handle WCS projections for plotting astronomical images. #606
Open

cvanelteren added the Wait Suspending current issue until further notice label Mar 7, 2026

cvanelteren marked this pull request as draft March 9, 2026 04:48

cvanelteren changed the title ~~Fix/wcs projection 606~~Feature: Add AstroPy SupportMar 10, 2026

cvanelteren force-pushed the fix/wcs-projection-606 branch 2 times, most recently from ba2ecaf to d9e8ccaCompare March 11, 2026 23:30

cvanelteren marked this pull request as ready for review July 17, 2026 04:15

cvanelteren removed the Wait Suspending current issue until further notice label Jul 17, 2026

cvanelteren self-assigned this Jul 21, 2026

cvanelteren added the help wanted Extra attention is needed label Jul 21, 2026

cvanelteren force-pushed the fix/wcs-projection-606 branch 2 times, most recently from c44d804 to 7b23360Compare August 13, 2026 04:53

cvanelteren added 10 commits August 13, 2026 14:54

Handle WCS projection objects in external containers
e8f2452
Closes#606

Black
2af15e6

Add native AstroAxes WCS integration
3aeb6a8
Route Astropy WCS projections through a native AstroAxes bridge instead of the external container, preserve per-axes transform dispatch for SubplotGrid, and keep shared panel labels stable for both cartesian and astro axes.

Refactor ticklabel sharing adapters
22fad05
Move logical ticklabel state access into the axes classes so Figure can share and hand off panel labels without branching on cartesian, geo, and astro subplot types.

Lazy-load AstroAxes integration
dc4eb22
Make the Astropy WCS bridge a true optional import by loading and registering AstroAxes only on WCS-specific access, while keeping the panel/share refactors and import behavior covered by tests.

Add basemap to Geo
899ef53

Fix WCS sharing after main merge
a7d77f7

cvanelteren added 2 commits August 13, 2026 14:54

Fix projection resolution edge cases
4775a12

fix: preserve named projection container compatibility
f7fa13f

cvanelteren force-pushed the fix/wcs-projection-606 branch from 7b23360 to f7fa13fCompare August 13, 2026 04:55

Merge branch 'main' into fix/wcs-projection-606
91b6168

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