Merge pull request #1564 from djhoese/bugfix-difference-compositor

Fix DifferenceCompositor ignoring YAML metadata

satpy/composites/__init__.py

@@ -208,13 +208,14 @@ def check_areas(self, data_arrays):
 class DifferenceCompositor(CompositeBase):
     """Make the difference of two data arrays."""
 
-    def __call__(self, projectables, nonprojectables=None, **info):
+    def __call__(self, projectables, nonprojectables=None, **attrs):
         """Generate the composite."""
         if len(projectables) != 2:
             raise ValueError("Expected 2 datasets, got %d" % (len(projectables),))
         projectables = self.match_data_arrays(projectables)
         info = combine_metadata(*projectables)
         info['name'] = self.attrs['name']
+        info.update(attrs)
 
         proj = projectables[0] - projectables[1]
         proj.attrs = info

satpy/tests/test_composites.py

@@ -267,8 +267,9 @@ def test_basic_diff(self):
         """Test that a basic difference composite works."""
         from satpy.composites import DifferenceCompositor
         comp = DifferenceCompositor(name='diff')
-        res = comp((self.ds1, self.ds2))
+        res = comp((self.ds1, self.ds2), standard_name='temperature_difference')
         np.testing.assert_allclose(res.values, -2)
+        assert res.attrs.get('standard_name') == 'temperature_difference'
 
     def test_bad_areas_diff(self):
         """Test that a difference where resolutions are different fails."""