Add tests to keep sun-earth distance-corrected reflectances as dask a…

…rrays

satpy/readers/utils.py

@@ -17,20 +17,20 @@
 # satpy.  If not, see <http://www.gnu.org/licenses/>.
 """Helper functions for satpy readers."""
 
-import logging
-
-from contextlib import closing
-import tempfile
 import bz2
+import logging
 import os
 import shutil
-import numpy as np
-import pyproj
+import tempfile
 import warnings
+from contextlib import closing
 from io import BytesIO
 from subprocess import Popen, PIPE
-from pyresample.geometry import AreaDefinition
 
+import numpy as np
+import pyproj
+import xarray as xr
+from pyresample.geometry import AreaDefinition
 from satpy import CHUNK_SIZE
 
 try:
@@ -334,9 +334,10 @@ def apply_earthsun_distance_correction(reflectance, utc_date=None):
     utc_date = get_array_date(reflectance, utc_date)
     sun_earth_dist = sun_earth_distance_correction(utc_date)
 
-    reflectance = reflectance * sun_earth_dist * sun_earth_dist
     reflectance.attrs['sun_earth_distance_correction_applied'] = True
     reflectance.attrs['sun_earth_distance_correction_factor'] = sun_earth_dist
+    with xr.set_options(keep_attrs=True):
+        reflectance = reflectance * sun_earth_dist * sun_earth_dist
     return reflectance
 
 
@@ -348,5 +349,6 @@ def remove_earthsun_distance_correction(reflectance, utc_date=None):
 
     reflectance.attrs['sun_earth_distance_correction_applied'] = False
     reflectance.attrs['sun_earth_distance_correction_factor'] = sun_earth_dist
-    reflectance = reflectance / (sun_earth_dist * sun_earth_dist)
+    with xr.set_options(keep_attrs=True):
+        reflectance = reflectance / (sun_earth_dist * sun_earth_dist)
     return reflectance

satpy/tests/reader_tests/test_utils.py

@@ -17,15 +17,16 @@
 # satpy.  If not, see <http://www.gnu.org/licenses/>.
 """Testing of helper functions."""
 
+import os
 import unittest
 from datetime import datetime
 from unittest import mock
-import os
-import xarray as xr
+
+import dask.array as da
 import numpy as np
 import numpy.testing
 import pyresample.geometry
-
+import xarray as xr
 from satpy.readers import utils as hf
 
 
@@ -335,16 +336,16 @@ class TestSunEarthDistanceCorrection(unittest.TestCase):
     """Tests for applying Sun-Earth distance correction to reflectance."""
 
     def setUp(self):
-        """"Create input / output arrays for the tests."""
+        """Create input / output arrays for the tests."""
         self.test_date = datetime(2020, 8, 15, 13, 0, 40)
 
-        raw_refl = xr.DataArray(np.array([10., 20., 40., 1., 98., 50.]),
+        raw_refl = xr.DataArray(da.from_array([10., 20., 40., 1., 98., 50.]),
                                 attrs={'start_time': self.test_date,
                                        'scheduled_time': self.test_date})
 
-        corr_refl = xr.DataArray(np.array([10.50514689, 21.01029379,
-                                           42.02058758, 1.05051469,
-                                           102.95043957, 52.52573447]),
+        corr_refl = xr.DataArray(da.from_array([10.50514689, 21.01029379,
+                                                42.02058758, 1.05051469,
+                                                102.95043957, 52.52573447]),
                                  attrs={'start_time': self.test_date,
                                         'scheduled_time': self.test_date})
         self.raw_refl = raw_refl
@@ -379,14 +380,14 @@ def test_get_utc_time(self):
 
     def test_apply_sunearth_corr(self):
         """Test the correction of reflectances with sun-earth distance."""
-
         out_refl = hf.apply_earthsun_distance_correction(self.raw_refl)
         np.testing.assert_allclose(out_refl, self.corr_refl)
         self.assertTrue(out_refl.attrs['sun_earth_distance_correction_applied'])
+        assert isinstance(out_refl.data, da.Array)
 
     def test_remove_sunearth_corr(self):
         """Test the removal of the sun-earth distance correction."""
-
         out_refl = hf.remove_earthsun_distance_correction(self.corr_refl)
         np.testing.assert_allclose(out_refl, self.raw_refl)
         self.assertFalse(out_refl.attrs['sun_earth_distance_correction_applied'])
+        assert isinstance(out_refl.data, da.Array)