Make Dask Optional (#835)

* added downloaded examples directory to gitignore

* Dask in now a true optional dep.

* fixed some tests for cupy available but no dask case

* skipping dask tests if dask unavailable

Author: brendancol

.gitignore

@@ -95,3 +95,4 @@ dmypy.json
 
 # airspeed velocity
 .asv/
+xrspatial-examples/

xrspatial/aspect.py

@@ -1,13 +1,20 @@
+from __future__ import annotations
+
 from functools import partial
 from math import atan2
 from typing import Optional
 
-import dask.array as da
+try:
+    import dask.array as da
+except ImportError:
+    da = None
+
+
 import numpy as np
 import xarray as xr
 from numba import cuda
 
-from xrspatial.utils import ArrayTypeFunctionMapping, cuda_args, ngjit, not_implemented_func
+from xrspatial.utils import ArrayTypeFunctionMapping, cuda_args, ngjit
 
 # 3rd-party
 try:

xrspatial/classify.py

@@ -1,3 +1,5 @@
+from __future__ import annotations
+
 import warnings
 from functools import partial
 from typing import List, Optional
@@ -12,7 +14,11 @@
     class cupy(object):
         ndarray = False
 
-import dask.array as da
+try:
+    import dask.array as da
+except ImportError:
+    da = None
+
 import numba as nb
 import numpy as np
 

xrspatial/curvature.py

@@ -1,3 +1,5 @@
+from __future__ import annotations
+
 # std lib
 from functools import partial
 from typing import Optional, Union
@@ -9,7 +11,11 @@
     class cupy(object):
         ndarray = False
 
-import dask.array as da
+try:
+    import dask.array as da
+except ImportError:
+    da = None
+
 import numpy as np
 import xarray as xr
 from numba import cuda

xrspatial/datasets/__init__.py

@@ -1,6 +1,10 @@
 import os
 
-import dask.array as da
+try:
+    import dask.array as da
+except ImportError:
+    da = None
+
 import datashader as ds
 import noise
 import numpy as np
@@ -76,6 +80,10 @@ def make_terrain(
     terrain : xarray.DataArray
         2D array of generated terrain values.
     """
+
+    if da is None:
+        raise Exception("make terrain requires dask.Array (pip install dask)")
+
     def _func(arr, block_id=None):
         block_ystart = block_id[0] * arr.shape[0]
         block_xstart = block_id[1] * arr.shape[1]

xrspatial/focal.py

@@ -1,16 +1,26 @@
+from __future__ import annotations
+
+
 import copy
 from functools import partial
 from math import isnan
 import math
 
-import dask.array as da
 import numba as nb
 import numpy as np
 import pandas as pd
 import xarray as xr
+
 from numba import cuda, prange
 from xarray import DataArray
 
+
+try:
+    import dask.array as da
+except ImportError:
+    da = None
+
+
 try:
     import cupy
 except ImportError:

xrspatial/hillshade.py

@@ -2,8 +2,13 @@
 from functools import partial
 from typing import Optional
 
-import dask.array as da
 import numpy as np
+
+try:
+    import dask.array as da
+except ImportError:
+    da = None
+
 import xarray as xr
 from numba import cuda
 
@@ -178,12 +183,12 @@ def hillshade(agg: xr.DataArray,
             out = _run_cupy(agg.data, azimuth, angle_altitude)
 
     # dask + cupy case
-    elif (has_cuda_and_cupy() and isinstance(agg.data, da.Array) and
+    elif (has_cuda_and_cupy() and da is not None and isinstance(agg.data, da.Array) and
             is_cupy_backed(agg)):
         raise NotImplementedError("Dask/CuPy hillshade not implemented")
 
     # dask + numpy case
-    elif isinstance(agg.data, da.Array):
+    elif da is not None and isinstance(agg.data, da.Array):
         out = _run_dask_numpy(agg.data, azimuth, angle_altitude)
 
     else:

xrspatial/multispectral.py

@@ -1,7 +1,8 @@
+from __future__ import annotations
+
 import warnings
 from math import sqrt
 
-import dask.array as da
 import numba as nb
 import numpy as np
 import xarray as xr
@@ -18,6 +19,11 @@
     class cupy(object):
         ndarray = False
 
+try:
+    import dask.array as da
+except ImportError:
+    da = None
+
 
 @ngjit
 def _arvi_cpu(nir_data, red_data, blue_data):

xrspatial/perlin.py

@@ -1,3 +1,5 @@
+from __future__ import annotations
+
 # std lib
 from functools import partial
 
@@ -11,7 +13,11 @@
     class cupy(object):
         ndarray = False
 
-import dask.array as da
+try:
+    import dask.array as da
+except ImportError:
+    da = None
+
 import numba as nb
 from numba import cuda, jit
 

xrspatial/proximity.py

@@ -1,6 +1,10 @@
 from math import sqrt
 
-import dask.array as da
+try:
+    import dask.array as da
+except ImportError:
+    da = None
+
 import numpy as np
 import xarray as xr
 from numba import prange
@@ -619,7 +623,7 @@ def _process_dask(raster, xs, ys):
         # numpy case
         result = _process_numpy(raster.data, xs, ys)
 
-    elif isinstance(raster.data, da.Array):
+    elif da is not None and isinstance(raster.data, da.Array):
         # dask + numpy case
         xs = da.from_array(xs, chunks=(raster.chunks))
         ys = da.from_array(ys, chunks=(raster.chunks))