utils to turn all transformations to affine

src/spatialdata/transformations/_utils.py

@@ -14,6 +14,7 @@
 from spatialdata._types import ArrayLike
 
 if TYPE_CHECKING:
+    from spatialdata._core.spatialdata import SpatialData
     from spatialdata.models import SpatialElement
     from spatialdata.models._utils import MappingToCoordinateSystem_t
     from spatialdata.transformations.transformations import Affine, BaseTransformation, Scale
@@ -254,3 +255,30 @@ def scale_radii(radii: ArrayLike, affine: Affine, axes: tuple[str, ...]) -> Arra
     new_radii = radii * scale_factor
     assert isinstance(new_radii, np.ndarray)
     return new_radii
+
+
+def convert_transformations_to_affine(sdata: SpatialData, coordinate_system: str) -> None:
+    """
+    Convert all transformations to the given coordinate system to affine transformations.
+
+    Parameters
+    ----------
+    coordinate_system
+        The coordinate system to convert to.
+
+    Notes
+    -----
+    The new transformations are modified only in-memory. If you want to save the changes to disk please call
+    `SpatialData.write_transformations()`.
+    """
+    from spatialdata.transformations.operations import get_transformation, set_transformation
+    from spatialdata.transformations.transformations import Affine, _get_affine_for_element
+
+    for _, _, element in sdata.gen_spatial_elements():
+        transformations = get_transformation(element, get_all=True)
+        assert isinstance(transformations, dict)
+        if coordinate_system in transformations:
+            t = transformations[coordinate_system]
+            if not isinstance(t, Affine):
+                affine = _get_affine_for_element(element, t)
+                set_transformation(element, transformation=affine, to_coordinate_system=coordinate_system)

tests/transformations/test_transformations_utils.py

@@ -0,0 +1,15 @@
+from spatialdata.transformations._utils import convert_transformations_to_affine
+from spatialdata.transformations.operations import get_transformation, set_transformation
+from spatialdata.transformations.transformations import Affine, Scale, Sequence, Translation
+
+
+def test_convert_transformations_to_affine(full_sdata):
+    translation = Translation([1, 2, 3], axes=("x", "y", "z"))
+    scale = Scale([1, 2, 3], axes=("x", "y", "z"))
+    sequence = Sequence([translation, scale])
+    for _, _, element in full_sdata.gen_spatial_elements():
+        set_transformation(element, transformation=sequence, to_coordinate_system="test")
+    convert_transformations_to_affine(full_sdata, "test")
+    for _, _, element in full_sdata.gen_spatial_elements():
+        t = get_transformation(element, "test")
+        assert isinstance(t, Affine)