Fix two WCS bugs

CHANGES.rst

@@ -13,6 +13,8 @@
 - Add support for asdf-transform-schemas 0.6 and asdf-coordinates-schemas 0.4. [#279]
 - Ignore UnitsWarnings emitted by astropy when converting units to VO format. [#281]
 - Add support for new astronomy-1.1.0 manifest. [#282]
+- Serialize ``pixel_shape`` on ``astropy.wcs.WCS``. [#276]
+- Accept a gwcs object when serializing ``SlicedLowLevelWCS``. [#276]
 
 0.7.1 (2025-02-12)
 ------------------

asdf_astropy/converters/wcs/tests/test_wcs.py

@@ -6,11 +6,10 @@
 from astropy.utils.data import get_pkg_data_filename, get_pkg_data_filenames
 from astropy.wcs import WCS, DistortionLookupTable, FITSFixedWarning, Sip
 
+from asdf_astropy.exceptions import InconsistentWCSError
 from asdf_astropy.testing.helpers import assert_wcs_roundtrip
 
-_astropy_test_header_filenames = list(get_pkg_data_filenames("tests/data/maps", "astropy.wcs", "*.hdr")) + list(
-    get_pkg_data_filenames("tests/data/spectra", "astropy.wcs", "*.hdr"),
-)
+_astropy_test_header_filenames = list(get_pkg_data_filenames("tests/data/maps", "astropy.wcs", "*.hdr"))
 
 _astropy_test_fits_filenames = [
     get_pkg_data_filename(f"tests/data/{fn}", "astropy.wcs")
@@ -118,3 +117,11 @@ def test_astropy_data_fits_roundtrip(fn, tmp_path, version):
             wcs = WCS(ff[0].header, ff)
 
         assert_wcs_roundtrip(wcs, tmp_path, version)
+
+
+@pytest.mark.parametrize("attr", ["pixel_shape", "pixel_bounds"])
+def test_failure_to_convert_inconsistent(tmp_path, attr):
+    wcs = create_wcs_with_attrs()
+    wcs.naxis -= 1
+    with pytest.raises(InconsistentWCSError, match="does not match naxis"):
+        assert_wcs_roundtrip(wcs, tmp_path)

asdf_astropy/converters/wcs/wcs.py

@@ -1,8 +1,10 @@
 from asdf.extension import Converter
 
+from asdf_astropy.exceptions import InconsistentWCSError
+
 # These attributes don't end up in the hdulist and
 # instead will be stored in "attrs"
-_WCS_ATTRS = ("naxis", "colsel", "keysel", "key", "pixel_bounds")
+_WCS_ATTRS = ("naxis", "colsel", "keysel", "key", "pixel_bounds", "pixel_shape")
 
 
 class WCSConverter(Converter):
@@ -18,20 +20,34 @@ def from_yaml_tree(self, node, tag, ctx):
         if naxis := attrs.pop("naxis"):
             hdulist[0].header["naxis"] = naxis
 
+        # pop attrs that are not valid kwargs
+        pixel_shape = attrs.pop("pixel_shape")
         pixel_bounds = attrs.pop("pixel_bounds")
 
         wcs = WCS(hdulist[0].header, fobj=hdulist, **attrs)
 
+        wcs.pixel_shape = pixel_shape
+        wcs.pixel_bounds = pixel_bounds
+
         if wcs.sip is not None:
             # work around a bug in astropy where sip headers lose precision
             # see https://github.com/astropy/astropy/issues/17334
             wcs.sip = wcs._read_sip_kw(hdulist[0].header, attrs.get("key", " "))
             wcs.wcs.set()
 
-        wcs.pixel_bounds = pixel_bounds
         return wcs
 
     def to_yaml_tree(self, wcs, tag, ctx):
+        # Check that wcs is consistent. Astropy inconsistently checks
+        # that certain expected attributes match. We need to check this
+        # here to prevent writing inconsistent files that would be problematic
+        # to open.
+        if naxis := wcs.naxis:
+            for attr in ("pixel_shape", "pixel_bounds"):
+                if value := getattr(wcs, attr):
+                    if len(value) != naxis:
+                        msg = f"{attr} shape ({len(value)}) does not match naxis ({naxis})"
+                        raise InconsistentWCSError(msg)
         hdulist = wcs.to_fits(relax=True)
         attrs = {a: getattr(wcs, a) for a in _WCS_ATTRS if hasattr(wcs, a)}
         return {"hdulist": hdulist, "attrs": attrs}

asdf_astropy/exceptions.py

@@ -0,0 +1,4 @@
+class InconsistentWCSError(ValueError):
+    """
+    An error for a WCS with inconsistent attributes.
+    """

asdf_astropy/extensions.py

@@ -540,6 +540,7 @@
 
 
 _ASTROPY_EXTENSION_MANIFEST_URIS = [
+    "asdf://astropy.org/astropy/manifests/astropy-1.4.0",
     "asdf://astropy.org/astropy/manifests/astropy-1.3.0",
     "asdf://astropy.org/astropy/manifests/astropy-1.2.0",
     "asdf://astropy.org/astropy/manifests/astropy-1.1.0",

asdf_astropy/resources/manifests/astropy-1.4.0.yaml

@@ -0,0 +1,73 @@
+id: asdf://astropy.org/astropy/manifests/astropy-1.4.0
+extension_uri: asdf://astropy.org/astropy/extensions/astropy-1.4.0
+title: Astropy extension 1.4.0
+description: |-
+  A set of tags for serializing astropy objects.  This does not include most
+  model classes, which are handled by an implementation of the ASDF
+  transform extension.
+asdf_standard_requirement:
+  gte: 1.6.0
+tags:
+- tag_uri: tag:astropy.org:astropy/time/timedelta-1.1.0
+  schema_uri: http://astropy.org/schemas/astropy/time/timedelta-1.1.0
+  title: Represents an instance of TimeDelta from astropy
+  description: |-
+    Represents the time difference between two times.
+- tag_uri: tag:astropy.org:astropy/fits/fits-1.1.0
+  schema_uri: http://astropy.org/schemas/astropy/fits/fits-1.1.0
+  title: A FITS file inside of an ASDF file.
+  description: |-
+    This schema is useful for distributing ASDF files that can
+    automatically be converted to FITS files by specifying the exact
+    content of the resulting FITS file.
+
+    Not all kinds of data in FITS are directly representable in ASDF.
+    For example, applying an offset and scale to the data using the
+    `BZERO` and `BSCALE` keywords.  In these cases, it will not be
+    possible to store the data in the native format from FITS and also
+    be accessible in its proper form in the ASDF file.
+
+    Only image and binary table extensions are supported.
+- tag_uri: tag:astropy.org:astropy/table/table-1.2.0
+  schema_uri: http://astropy.org/schemas/astropy/table/table-1.2.0
+  title: A table.
+  description: |-
+    A table is represented as a list of columns, where each entry is a
+    [column](ref:http://stsci.edu/schemas/asdf/table/column-1.1.0)
+    object, containing the data and some additional information.
+
+    The data itself may be stored inline as text, or in binary in either
+    row- or column-major order by use of the `strides` property on the
+    individual column arrays.
+
+    Each column in the table must have the same first (slowest moving)
+    dimension.
+- tag_uri: tag:astropy.org:astropy/transform/units_mapping-1.1.0
+  schema_uri: http://astropy.org/schemas/astropy/transform/units_mapping-1.1.0
+  title: Mapper that operates on the units of the input.
+  description: |-
+    This transform operates on the units of the input, first converting to
+    the expected input units, then assigning replacement output units without
+    further conversion.
+- tag_uri: tag:astropy.org:astropy/table/ndarraymixin-1.0.0
+  schema_uri: http://astropy.org/schemas/astropy/table/ndarraymixin-1.0.0
+  title: NdarrayMixin column.
+  description: |-
+    Represents an astropy.table.NdarrayMixin instance.
+- tag_uri: tag:astropy.org:astropy/wcs/slicedwcs-1.1.0
+  schema_uri: http://astropy.org/schemas/astropy/wcs/slicedwcs-1.1.0
+  title: Represents an instance of SlicedLowLevelWCS
+  description: |-
+    The SlicedLowLevelWCS class is a wrapper class for WCS that applies slices
+    to the WCS, allowing certain pixel and world dimensions to be retained or
+    dropped.
+
+    It manages the slicing and coordinate transformations while preserving
+    the underlying WCS object.
+- tag_uri: tag:astropy.org:astropy/wcs/wcs-1.0.0
+  schema_uri: http://astropy.org/schemas/astropy/wcs/wcs-1.0.0
+  title: FITS WCS (World Coordinate System) Converter
+  description: |-
+    Represents the FITS WCS object, the HDUlist of the FITS header is preserved
+    during serialization and during deserialization the WCS object is recreated
+    from the HDUlist.

asdf_astropy/resources/schemas/wcs/slicedwcs-1.1.0.yaml

@@ -0,0 +1,52 @@
+%YAML 1.1
+---
+$schema: "http://stsci.edu/schemas/yaml-schema/draft-01"
+id: "http://astropy.org/schemas/astropy/wcs/slicedwcs-1.1.0"
+
+title: Represents the SlicedLowLevelWCS object
+
+description: >-
+  The SlicedLowLevelWCS class is a wrapper class for WCS that applies slices
+  to the WCS, allowing certain pixel and world dimensions to be retained or
+  dropped.
+  It manages the slicing and coordinate transformations while preserving
+  the underlying WCS object.
+
+allOf:
+  - type: object
+    properties:
+      wcs:
+        anyOf:
+          # Known WCS objects
+          - tag: "tag:astropy.org:astropy/wcs/wcs-1*"
+          - tag: "tag:stsci.edu:gwcs/wcs-*"
+          - tag: "tag:astropy.org:astropy/wcs/slicedwcs-*"
+          - tag: "tag:sunpy.org:ndcube/resampledwcs-*"
+          - tag: "tag:sunpy.org:ndcube/ndcubesequence-*"
+          - tag: "tag:sunpy.org:ndcube/reorderedwcs-*"
+          - tag: "tag:sunpy.org:ndcube/compoundwcs-*"
+          # Allow anything else because any APE-14 compliant object is valid
+          - {}
+
+      slices_array:
+        type: array
+        items:
+          - oneOf:
+            - type: integer
+            - type: object
+              properties:
+                start:
+                  anyOf:
+                    - type: integer
+                    - type: "null"
+                stop:
+                  anyOf:
+                    - type: integer
+                    - type: "null"
+                step:
+                  anyOf:
+                    - type: integer
+                    - type: "null"
+
+
+    required: ["wcs", "slices_array"]