binary(): type the dask+cupy meta so the lazy dtype matches float32

_run_dask_cupy_binary passed meta=cupy.array(()), which defaults to
float64, so the lazy dask array advertised float64 while the chunk
function _run_cupy_binary computes float32. The eager dtype fix in the
previous commit did not cover the advertised dask+cupy dtype, and the
existing tests only check the computed dtype (general_output_checks
computes before asserting), so the mismatch went unnoticed.

Pass meta=cupy.array((), dtype='f4') and assert the lazy dtype in
test_binary_dask_cupy. Same advertised-vs-computed class as aspect #2682
and focal #3217.

Author: brendancol

xrspatial/classify.py

@@ -98,7 +98,8 @@ def _run_cupy_binary(data, values):
 
 
 def _run_dask_cupy_binary(data, values_cupy):
-    out = data.map_blocks(lambda da: _run_cupy_binary(da, values_cupy), meta=cupy.array(()),
+    out = data.map_blocks(lambda da: _run_cupy_binary(da, values_cupy),
+                          meta=cupy.array((), dtype='f4'),
                           **_dask_task_name_kwargs('xrspatial.binary'))
     return out
 

xrspatial/tests/test_classify.py

@@ -69,6 +69,9 @@ def test_binary_dask_cupy(result_binary):
     values, expected_result = result_binary
     dask_cupy_agg = input_data(backend='dask+cupy')
     dask_cupy_result = binary(dask_cupy_agg, values)
+    # the lazy dask array must advertise the same dtype it computes, otherwise
+    # a downstream consumer reads float64 metadata for a float32 result
+    assert dask_cupy_result.data.dtype == np.float32
     general_output_checks(dask_cupy_agg, dask_cupy_result, expected_result, verify_dtype=True)