Fix axes configuration when adding existing zarr arrays (#1204)

* Change default behaviour for axes when creating zarrita array.

* add typehint.

* Update changelog.

* Add test.

* Fix type annotations for added test.

webknossos/Changelog.md

@@ -80,6 +80,7 @@ Removed the CZI installation extra from `pip install webknossos[all]` by default
 
 ### Fixed
 - Fixed an issue with merging annotations with compressed fallback layers.
+- Fixed an issue where adding a Zarr array with other axes than `cxyz` leads to an error. [#1204](https://github.com/scalableminds/webknossos-libs/pull/1204)
 
 
 

webknossos/tests/dataset/test_layer.py

@@ -0,0 +1,31 @@
+from pathlib import Path
+
+import numpy as np
+from zarrita import Array
+
+import webknossos as wk
+
+
+def test_add_mag_from_zarrarray(tmp_path: Path) -> None:
+    dataset = wk.Dataset(
+        tmp_path / "test_add_mag_from_zarrarray", voxel_size=(10, 10, 10)
+    )
+    layer = dataset.add_layer(
+        "color",
+        wk.COLOR_CATEGORY,
+        data_format="zarr3",
+        bounding_box=wk.BoundingBox((0, 0, 0), (16, 16, 16)),
+    )
+    zarr_mag_path = tmp_path / "zarr_data" / "mag1.zarr"
+    zarr_data = np.random.randint(0, 255, (16, 16, 16), dtype="uint8")
+    zarr_mag = Array.create(
+        store=zarr_mag_path, shape=(16, 16, 16), chunk_shape=(8, 8, 8), dtype="uint8"
+    )
+    zarr_mag[:] = zarr_data
+
+    layer.add_mag_from_zarrarray("1", zarr_mag_path, extend_layer_bounding_box=False)
+
+    assert layer.get_mag("1").read().shape == (1, 16, 16, 16)
+    assert layer.get_mag("1").info.num_channels == 1
+    assert layer.get_mag("1").info.dimension_names == ("c", "x", "y", "z")
+    assert (layer.get_mag("1").read()[0] == zarr_data).all()

webknossos/webknossos/dataset/_array.py

@@ -498,15 +498,43 @@ def info(self) -> ArrayInfo:
         from zarrita.sharding import ShardingCodec
 
         zarray = self._zarray
+        dimension_names: tuple[str, ...]
         if (names := getattr(zarray.metadata, "dimension_names", None)) is None:
-            dimension_names = ("c", "x", "y", "z")
+            if (shape := getattr(zarray.metadata, "shape", None)) is None:
+                raise ValueError(
+                    "Unable to determine the shape of the Zarrita Array. Neither dimension_names nor shape are present in the metadata file zarr.json."
+                )
+            else:
+                if len(shape) == 2:
+                    dimension_names = ("x", "y")
+                    num_channels = 1
+                elif len(shape) == 3:
+                    dimension_names = ("x", "y", "z")
+                    num_channels = 1
+                elif len(shape) == 4:
+                    dimension_names = ("c", "x", "y", "z")
+                    num_channels = shape[0]
+                else:
+                    raise ValueError(
+                        "Unusual shape for Zarrita array, please specify the dimension names in the metadata file zarr.json."
+                    )
         else:
             dimension_names = names
+            if (shape := getattr(zarray.metadata, "shape", None)) is None:
+                shape = VecInt.ones(dimension_names)
+            if "c" in dimension_names:
+                num_channels = zarray.metadata.shape[dimension_names.index("c")]
+            else:
+                num_channels = 1
         x_index, y_index, z_index = (
             dimension_names.index("x"),
             dimension_names.index("y"),
             dimension_names.index("z"),
         )
+        if "c" not in dimension_names:
+            shape = (num_channels,) + shape
+            dimension_names = ("c",) + dimension_names
+        array_shape = VecInt(shape, axes=dimension_names)
         if isinstance(zarray, Array):
             if len(zarray.codec_pipeline.codecs) == 1 and isinstance(
                 zarray.codec_pipeline.codecs[0], ShardingCodec
@@ -516,7 +544,7 @@ def info(self) -> ArrayInfo:
                 chunk_shape = sharding_codec.configuration.chunk_shape
                 return ArrayInfo(
                     data_format=DataFormat.Zarr3,
-                    num_channels=zarray.metadata.shape[0],
+                    num_channels=num_channels,
                     voxel_type=zarray.metadata.dtype,
                     compression_mode=self._has_compression_codecs(
                         sharding_codec.codec_pipeline.codecs
@@ -536,12 +564,13 @@ def info(self) -> ArrayInfo:
                             chunk_shape[z_index],
                         )
                     ),
+                    shape=array_shape,
                     dimension_names=dimension_names,
                 )
             chunk_shape = zarray.metadata.chunk_grid.configuration.chunk_shape
             return ArrayInfo(
                 data_format=DataFormat.Zarr3,
-                num_channels=zarray.metadata.shape[0],
+                num_channels=num_channels,
                 voxel_type=zarray.metadata.dtype,
                 compression_mode=self._has_compression_codecs(
                     zarray.codec_pipeline.codecs
@@ -550,13 +579,14 @@ def info(self) -> ArrayInfo:
                     chunk_shape[x_index], chunk_shape[y_index], chunk_shape[z_index]
                 )
                 or Vec3Int.full(1),
+                shape=array_shape,
                 chunks_per_shard=Vec3Int.full(1),
                 dimension_names=dimension_names,
             )
         else:
             return ArrayInfo(
                 data_format=DataFormat.Zarr,
-                num_channels=zarray.metadata.shape[0],
+                num_channels=num_channels,
                 voxel_type=zarray.metadata.dtype,
                 compression_mode=zarray.metadata.compressor is not None,
                 chunk_shape=Vec3Int(
@@ -565,6 +595,7 @@ def info(self) -> ArrayInfo:
                     zarray.metadata.chunks[z_index],
                 )
                 or Vec3Int.full(1),
+                shape=array_shape,
                 chunks_per_shard=Vec3Int.full(1),
                 dimension_names=dimension_names,
             )
@@ -634,9 +665,13 @@ def create(cls, path: Path, array_info: ArrayInfo) -> "ZarritaArray":
     def read(self, bbox: NDBoundingBox) -> np.ndarray:
         shape = bbox.size.to_tuple()
         zarray = self._zarray
-        slice_tuple = (slice(None),) + bbox.to_slices()
         with _blosc_disable_threading():
-            data = zarray[slice_tuple]
+            try:
+                slice_tuple = (slice(None),) + bbox.to_slices()
+                data = zarray[slice_tuple]
+            except IndexError:
+                # The data is stored without channel axis
+                data = zarray[bbox.to_slices()]
 
         shape_with_channels = (self.info.num_channels,) + shape
         if data.shape != shape_with_channels:

webknossos/webknossos/dataset/layer.py

@@ -1485,6 +1485,7 @@ def _setup_mag(self, mag: Mag, path: Optional[str] = None) -> None:
                 info.chunk_shape,
                 info.chunks_per_shard,
                 info.compression_mode,
+                info.shape,
                 False,
                 UPath(resolved_path),
             )

webknossos/webknossos/dataset/mag_view.py

@@ -125,6 +125,7 @@ def __init__(
         chunk_shape: Vec3Int,
         chunks_per_shard: Vec3Int,
         compression_mode: bool,
+        shape: Optional[VecInt] = None,
         create: bool = False,
         path: Optional[UPath] = None,
     ) -> None:
@@ -145,7 +146,9 @@ def __init__(
                 layer.num_channels,
                 *VecInt.ones(layer.bounding_box.axes),
                 axes=("c",) + layer.bounding_box.axes,
-            ),
+            )
+            if shape is None
+            else shape,
             dimension_names=("c",) + layer.bounding_box.axes,
         )
         if create: