attempts to create a writer

.isort.cfg

@@ -1,5 +1,5 @@
 [settings]
-known_third_party = cv2,dask,napari,numpy,pytest,requests,scipy,setuptools,skimage,vispy,zarr
+known_third_party = cv2,dask,numpy,pytest,requests,scipy,setuptools,skimage,vispy,zarr
 multi_line_output=6
 include_trailing_comma=False
 force_grid_wrap=0

.pre-commit-config.yaml

@@ -44,11 +44,11 @@ repos:
           - --autofix
 
   - repo: https://gitlab.com/pycqa/flake8
-    rev: 3.8.3
+    rev: 3.8.4
     hooks:
       - id: flake8
         additional_dependencies: [
-          flake8-blind-except,
+          # flake8-blind-except, FIXME
           flake8-builtins,
           flake8-rst-docstrings,
           flake8-logging-format,
@@ -74,7 +74,7 @@ repos:
           --disallow-untyped-defs,
           --ignore-missing-imports,
         ]
-        exclude: tests/*|setup.py
+        exclude: tests/|setup.py
 
   - repo: https://github.com/adrienverge/yamllint.git
     rev: v1.24.2

environment.yml

@@ -1,10 +1,10 @@
-#name: z
+name: z
 channels:
-  - defaults
   - ome
   - conda-forge
+  - defaults
 dependencies:
-  - napari
+  - pyqt
   - flake8
   - ipython
   - mypy
@@ -20,6 +20,7 @@ dependencies:
   - xarray
   - zarr >= 2.4.0
   - pip:
+      - napari
       - pre-commit
       - pytest-qt
 # python.app -- only install on OSX:

ome_zarr/data.py

@@ -12,6 +12,7 @@
 from skimage.segmentation import clear_border
 
 from .scale import Scaler
+from .writer import write_multiscale
 
 CHANNEL_DIMENSION = 1
 
@@ -92,17 +93,6 @@ def rgb_to_5d(pixels: np.ndarray) -> List:
     return video
 
 
-def write_multiscale(pyramid: List, group: zarr.Group) -> None:
-    """Write a pyramid with multiscale metadata to disk."""
-    paths = []
-    for path, dataset in enumerate(pyramid):
-        group.create_dataset(str(path), data=pyramid[path])
-        paths.append({"path": str(path)})
-
-    multiscales = [{"version": "0.1", "datasets": paths}]
-    group.attrs["multiscales"] = multiscales
-
-
 def create_zarr(
     zarr_directory: str,
     method: Callable[..., Tuple[List, List]] = coins,

ome_zarr/io.py

@@ -13,6 +13,7 @@
 
 import dask.array as da
 import requests
+import zarr
 
 from .types import JSONDict
 
@@ -106,8 +107,12 @@ class LocalZarrLocation(BaseZarrLocation):
     Uses the :module:`json` library for loading JSON from disk.
     """
 
-    def __init__(self, path: Path) -> None:
+    def __init__(self, path: Path, mode: str = "r") -> None:
         self.__path: Path = path
+        self.mode = mode
+        if mode in ("w", "a") and not self.__path.exists():
+            _ = zarr.DirectoryStore(self.basename())
+            LOGGER.debug("Created DirectoryStore %s", self.basename())
         super().__init__()
 
     def basename(self) -> str:
@@ -132,8 +137,7 @@ def get_json(self, subpath: str) -> JSONDict:
         If a file does not exist, an empty response is returned rather
         than an exception.
         """
-        filename = self.__path / subpath
-
+        filename = self.subpath(subpath)
         if not os.path.exists(filename):
             LOGGER.debug(f"{filename} does not exist")
             return {}
@@ -189,7 +193,7 @@ def get_json(self, subpath: str) -> JSONDict:
             return {}
 
 
-def parse_url(path: str) -> Optional[BaseZarrLocation]:
+def parse_url(path: str, mode: str = "r") -> Optional[BaseZarrLocation]:
     """Convert a path string or URL to a BaseZarrLocation subclass.
 
     >>> parse_url('does-not-exist')
@@ -199,12 +203,15 @@ def parse_url(path: str) -> Optional[BaseZarrLocation]:
         return LocalZarrLocation(Path(path))
     else:
         result = urlparse(path)
-        zarr: Optional[BaseZarrLocation] = None
+        zarr_loc: Optional[BaseZarrLocation] = None
         if result.scheme in ("", "file"):
             # Strips 'file://' if necessary
-            zarr = LocalZarrLocation(Path(result.path))
+            zarr_loc = LocalZarrLocation(Path(result.path), mode=mode)
+
         else:
-            zarr = RemoteZarrLocation(path)
-        if zarr.exists():
-            return zarr
+            if mode != "r":
+                raise ValueError("Remote locations are read only")
+            zarr_loc = RemoteZarrLocation(path)
+        if zarr_loc.exists() or (mode in ("a", "w")):
+            return zarr_loc
     return None

ome_zarr/reader.py

@@ -354,6 +354,7 @@ def __init__(self, node: Node) -> None:
             node.metadata["visible"] = visibles
             node.metadata["contrast_limits"] = contrast_limits
             node.metadata["colormap"] = colormaps
+
         except Exception as e:
             LOGGER.error(f"failed to parse metadata: {e}")
 

ome_zarr/writer.py

@@ -0,0 +1,86 @@
+"""Image writer utility
+
+"""
+import logging
+from typing import Any, List, Tuple, Union
+
+import numpy as np
+import zarr
+
+from .scale import Scaler
+from .types import JSONDict
+
+LOGGER = logging.getLogger("ome_zarr.writer")
+
+
+def write_multiscale(
+    pyramid: List, group: zarr.Group, chunks: Union[Tuple[Any, ...], int] = None,
+) -> None:
+    """Write a pyramid with multiscale metadata to disk."""
+    paths = []
+    for path, dataset in enumerate(pyramid):
+        # TODO: chunks here could be different per layer
+        group.create_dataset(str(path), data=dataset, chunks=chunks)
+        paths.append({"path": str(path)})
+
+    multiscales = [{"version": "0.1", "datasets": paths}]
+    group.attrs["multiscales"] = multiscales
+
+
+def write_image(
+    image: np.ndarray,
+    group: zarr.Group,
+    chunks: Union[Tuple[Any, ...], int] = None,
+    byte_order: Union[str, List[str]] = "tczyx",
+    scaler: Scaler = Scaler(),
+    **metadata: JSONDict,
+) -> None:
+    """Writes an image to the zarr store according to ome-zarr specification
+
+    Parameters
+    ----------
+    image: np.ndarray
+      the image data to save. A downsampling of the data will be computed
+      if the scaler argument is non-None.
+    group: zarr.Group
+      the group within the zarr store to store the data in
+    chunks: int or tuple of ints,
+      size of the saved chunks to store the image
+    byte_order: str or list of str, default "tczyx"
+      combination of the letters defining the order
+      in which the dimensions are saved
+    scaler: Scaler
+      Scaler implementation for downsampling the image argument. If None,
+      no downsampling will be performed.
+    """
+
+    if image.ndim > 5:
+        raise ValueError("Only images of 5D or less are supported")
+
+    shape_5d: Tuple[Any, ...] = (*(1,) * (5 - image.ndim), *image.shape)
+    image = image.reshape(shape_5d)
+
+    if chunks is not None:
+        chunks = _retuple(chunks, shape_5d)
+
+    if scaler is not None:
+        image = scaler.nearest(image)
+    else:
+        LOGGER.debug("disabling pyramid")
+        image = [image]
+
+    write_multiscale(image, group, chunks=chunks)
+    group.attrs.update(metadata)
+
+
+def _retuple(
+    chunks: Union[Tuple[Any, ...], int], shape: Tuple[Any, ...]
+) -> Tuple[Any, ...]:
+
+    _chunks: Tuple[Any, ...]
+    if isinstance(chunks, int):
+        _chunks = (chunks,)
+    else:
+        _chunks = chunks
+
+    return (*shape[: (5 - len(_chunks))], *_chunks)

tests/conftest.py

@@ -0,0 +1,10 @@
+def pytest_addoption(parser):
+    """
+    add `--show-viewer` as a valid command line flag
+    """
+    parser.addoption(
+        "--show-viewer",
+        action="store_true",
+        default=False,
+        help="don't show viewer during tests",
+    )

tests/test_napari.py

@@ -2,19 +2,11 @@
 
 import numpy as np
 import pytest
-from napari.conftest import make_test_viewer  # noqa
 
 from ome_zarr.data import astronaut, create_zarr
 from ome_zarr.napari import napari_get_reader
 
 
-@pytest.fixture(autouse=True, scope="session")
-def load_napari_conftest(pytestconfig):
-    from napari import conftest
-
-    pytestconfig.pluginmanager.register(conftest, "napari-conftest")
-
-
 class TestNapari:
     @pytest.fixture(autouse=True)
     def initdir(self, tmpdir):
@@ -67,9 +59,9 @@ def test_label(self):
     @pytest.mark.skipif(
         sys.version_info < (3, 7), reason="on_draw is missing in napari < 0.4.0",
     )
-    def test_viewer(self, make_test_viewer):  # noqa
+    def test_viewer(self, make_napari_viewer):  # noqa
         """example of testing the viewer."""
-        viewer = make_test_viewer()
+        viewer = make_napari_viewer()
 
         shapes = [(4000, 3000), (2000, 1500), (1000, 750), (500, 375)]
         np.random.seed(0)

tests/test_writer.py

@@ -0,0 +1,44 @@
+import numpy as np
+import pytest
+import zarr
+
+from ome_zarr.io import parse_url
+from ome_zarr.reader import Multiscales, Reader
+from ome_zarr.scale import Scaler
+from ome_zarr.writer import write_image
+
+
+class TestWriter:
+    @pytest.fixture(autouse=True)
+    def initdir(self, tmpdir):
+        self.path = tmpdir.mkdir("data")
+        self.store = zarr.DirectoryStore(self.path)
+        self.root = zarr.group(store=self.store)
+        self.group = self.root.create_group("test")
+
+    def create_data(self, shape, dtype=np.uint8, mean_val=10):
+        rng = np.random.default_rng(0)
+        return rng.poisson(mean_val, size=shape).astype(dtype)
+
+    @pytest.fixture(params=((1, 2, 1, 256, 256),))
+    def shape(self, request):
+        return request.param
+
+    @pytest.fixture(params=[True, False], ids=["scale", "noop"])
+    def scaler(self, request):
+        if request.param:
+            return Scaler()
+        else:
+            return None
+
+    def test_writer(self, shape, scaler):
+
+        data = self.create_data(shape)
+        write_image(image=data, group=self.group, chunks=(128, 128), scaler=scaler)
+
+        # Verify
+        reader = Reader(parse_url(f"{self.path}/test"))
+        node = list(reader())[0]
+        assert Multiscales.matches(node.zarr)
+        assert node.data[0].shape == shape
+        assert node.data[0].chunks == ((1,), (2,), (1,), (128, 128), (128, 128))