Merge pull request #27 from lsst/tickets/DM-39243

DM-39243: Add a factory method for OwnedImagePlanes

.github/workflows/rebase_checker.yaml

@@ -1,4 +1,3 @@
----
 name: Check that 'main' is not merged into the development branch
 
 on: pull_request

python/lsst/cell_coadds/_cell_coadd_builder.py

@@ -23,7 +23,7 @@
 
 from abc import ABCMeta, abstractmethod
 from collections.abc import Iterable, Mapping
-from typing import Any, ClassVar
+from typing import Any, ClassVar, cast
 
 import lsst.geom
 import lsst.pex.config as pexConfig
@@ -265,7 +265,7 @@ def run(  # type: ignore[override] # TODO: Remove after DM-34696 is fixed.
         common = CommonComponents(
             units=CoaddUnits.nJy,
             wcs=patchInfo.wcs,
-            band=quantumDataId.get("band", None),
+            band=cast(str, quantumDataId.get("band", "")),
             identifiers=PatchIdentifiers.from_data_id(quantumDataId),
         )
 

python/lsst/cell_coadds/_common_components.py

@@ -44,6 +44,11 @@ class CoaddUnits(enum.Enum):
     flux unit other than nJy).
     """
 
+    legacy = enum.auto()
+    """Pixels in semi-arbitrary unit obtained by scaling the warps to a common
+    zeropoint (typically 27).
+    """
+
     nJy = enum.auto()
     """Pixels represent flux in nanojanskies.
     """

python/lsst/cell_coadds/_identifiers.py

@@ -76,7 +76,7 @@ def from_data_id(cls, data_id: DataCoordinate) -> PatchIdentifiers:
             skymap=cast(str, data_id["skymap"]),
             tract=cast(int, data_id["tract"]),
             patch=Index2D(x=patch_record.cell_x, y=patch_record.cell_y),
-            band=data_id.get("band"),
+            band=cast(str, data_id.get("band")),
         )
 
 
@@ -111,7 +111,7 @@ def from_data_id(  # type: ignore [override]
             skymap=cast(str, data_id["skymap"]),
             tract=cast(int, data_id["tract"]),
             patch=Index2D(x=patch_record.cell_x, y=patch_record.cell_y),
-            band=data_id.get("band"),
+            band=cast(str, data_id.get("band")),
             cell=cell,
         )
 

python/lsst/cell_coadds/_image_planes.py

@@ -29,12 +29,12 @@
 
 from abc import ABC, abstractmethod
 from collections.abc import Callable, Sequence
-from typing import TYPE_CHECKING
+from typing import TYPE_CHECKING, Self
 
 from lsst.afw.image import MaskedImageF
 
 if TYPE_CHECKING:
-    from lsst.afw.image import Mask
+    from lsst.afw.image import Mask, MaskedImage
     from lsst.geom import Box2I
 
     from .typing_helpers import ImageLike
@@ -116,6 +116,39 @@ def __init__(
         self._mask_fractions = mask_fractions
         self._noise_realizations = tuple(noise_realizations)
 
+    @classmethod
+    def from_masked_image(
+        cls,
+        masked_image: MaskedImage,
+        mask_fractions: ImageLike | None = None,
+        noise_realizations: Sequence[ImageLike] = (),
+    ) -> Self:
+        """Construct from an `lsst.afw.image.MaskedImage`.
+
+        Parameters
+        ----------
+        masked_image : `~lsst.afw.image.MaskedImage`
+            The image to construct from. The image, mask and variance planes
+            of ``masked_image`` will be used as the image, mask and variance
+            planes of the constructed object.
+        mask_fractions : `ImageLike`, optional
+            The mask fractions image.
+        noise_realizations : `Sequence` [`ImageLike`], optional
+            The noise realizations.
+
+        Returns
+        -------
+        self : `OwnedImagePlanes`
+            An instance of OwnedImagePlanes.
+        """
+        return cls(
+            image=masked_image.image,
+            mask=masked_image.mask,
+            variance=masked_image.variance,
+            mask_fractions=mask_fractions,
+            noise_realizations=noise_realizations,
+        )
+
     @property
     def bbox(self) -> Box2I:
         # Docstring inherited.

python/lsst/cell_coadds/_multiple_cell_coadd.py

@@ -72,6 +72,7 @@ def __init__(
         self._common = common
         cells_builder = GridContainer[SingleCellCoadd](self._grid.shape)
         self._mask_fraction_names: set[str] = set()
+
         for cell in cells:
             index = cell.identifiers.cell
             cells_builder[index] = cell
@@ -97,9 +98,17 @@ def __init__(
         if n_noise_realizations:
             n_noise_realizations.add(self._n_noise_realizations)
             raise ValueError(
-                f"Inconsistent number of noise realizations ({n_noise_realizations}) betwen cells."
+                f"Inconsistent number of noise realizations ({n_noise_realizations}) between cells."
             )
-        max_inner_bbox = Box2I(self._cells.first.inner.bbox.getMin(), self._cells.last.inner.bbox.getMax())
+
+        # Finish the construction without relying on the first and last of
+        # self._cells so we can construct an instance with partial list.
+        indices = list(cells_builder.indices())
+        max_inner_bbox = Box2I(
+            grid.bbox_of(indices[0]).getMin(),
+            grid.bbox_of(indices[-1]).getMax(),
+        )
+
         if inner_bbox is None:
             inner_bbox = max_inner_bbox
         elif not max_inner_bbox.contains(inner_bbox):

tests/test_coadds.py

@@ -64,7 +64,7 @@ def setUpClass(cls) -> None:
         np.random.seed(42)
         data_id = test_utils.generate_data_id()
         common = CommonComponents(
-            units=CoaddUnits.nJy,
+            units=CoaddUnits.legacy,  # units here are arbitrary.
             wcs=test_utils.generate_wcs(),
             band=data_id["band"],
             identifiers=PatchIdentifiers.from_data_id(data_id),