fixed bug in dask+cupy args and added unit test

Author: brendancol

README.md

@@ -209,7 +209,7 @@ In the GIS world, rasters are used for representing continuous phenomena (e.g. e
 | Name | NumPy xr.DataArray | Dask xr.DataArray | CuPy GPU xr.DataArray | Dask GPU xr.DataArray |
 |:----------:|:----------------------:|:--------------------:|:-------------------:|:------:|
 | [Aspect](xrspatial/aspect.py) | ✅️ | ✅️ | ✅️ | ✅️ |
-| [Curvature](xrspatial/curvature.py) | ✅️ | | | ⚠️  |
+| [Curvature](xrspatial/curvature.py) | ✅️ |⚠️✅️ |⚠️✅️ | ⚠️✅️  |
 | [Hillshade](xrspatial/hillshade.py) | ✅️ | ✅️  | | |
 | [Slope](xrspatial/slope.py) | ✅️  | ✅️  | ✅️ | ⚠️✅️  |
 | [Terrain Generation](xrspatial/terrain.py) | ✅️ | ✅️ | ✅️ | |

xrspatial/curvature.py

@@ -15,8 +15,7 @@ class cupy(object):
 from numba import cuda
 
 # local modules
-from xrspatial.utils import (ArrayTypeFunctionMapping, cuda_args, get_dataarray_resolution, ngjit,
-                             not_implemented_func)
+from xrspatial.utils import (ArrayTypeFunctionMapping, cuda_args, get_dataarray_resolution, ngjit)
 
 
 @ngjit
@@ -84,10 +83,14 @@ def _run_cupy(data: cupy.ndarray,
 
     return out
 
+
 def _run_dask_cupy(data: da.Array,
-                    cellsize: Union[int, float]) -> da.Array:
+                   cellsize: Union[int, float]) -> da.Array:
     data = data.astype(cupy.float32)
-    _func = partial(_cpu, cellsize=cellsize)
+    cellsize_arr = cupy.array([float(cellsize)], dtype='f4')
+
+    _func = partial(_run_cupy, cellsize=cellsize_arr)
+
     out = data.map_overlap(_func,
                            depth=(1, 1),
                            boundary=cupy.nan,

xrspatial/tests/test_curvature.py

@@ -3,6 +3,7 @@
 
 from xrspatial import curvature
 from xrspatial.tests.general_checks import (assert_numpy_equals_cupy,
+                                            assert_numpy_equals_dask_cupy,
                                             assert_numpy_equals_dask_numpy, create_test_raster,
                                             cuda_and_cupy_available, general_output_checks)
 
@@ -87,9 +88,6 @@ def test_numpy_equals_cupy_random_data(random_data):
     numpy_agg = create_test_raster(random_data, backend='numpy')
     cupy_agg = create_test_raster(random_data, backend='cupy')
     assert_numpy_equals_cupy(numpy_agg, cupy_agg, curvature)
-    # NOTE: Dask + GPU code paths don't currently work because of
-    # dask casting cupy arrays to numpy arrays during
-    # https://github.com/dask/dask/issues/4842
 
 
 @pytest.mark.parametrize("size", [(2, 4), (10, 15)])
@@ -99,3 +97,13 @@ def test_numpy_equals_dask_random_data(random_data):
     numpy_agg = create_test_raster(random_data, backend='numpy')
     dask_agg = create_test_raster(random_data, backend='dask')
     assert_numpy_equals_dask_numpy(numpy_agg, dask_agg, curvature)
+
+
+@cuda_and_cupy_available
+@pytest.mark.parametrize("size", [(2, 4), (10, 15)])
+@pytest.mark.parametrize(
+    "dtype", [np.int32, np.int64, np.uint32, np.uint64, np.float32, np.float64])
+def test_numpy_equals_dask_cupy_random_data(random_data):
+    numpy_agg = create_test_raster(random_data, backend='numpy')
+    dask_cupy_agg = create_test_raster(random_data, backend='dask+cupy')
+    assert_numpy_equals_dask_cupy(numpy_agg, dask_cupy_agg, curvature, atol=1e-6, rtol=1e-6)