Bugfix of link_coords

satpy/tests/writer_tests/test_cf.py

@@ -621,11 +621,15 @@ def test_link_coords(self):
 
         data = [[1, 2], [3, 4]]
         lon = np.zeros((2, 2))
+        lon2 = np.zeros((1, 2, 2))
         lat = np.ones((2, 2))
         datasets = {
             'var1': xr.DataArray(data=data, dims=('y', 'x'), attrs={'coordinates': 'lon lat'}),
             'var2': xr.DataArray(data=data, dims=('y', 'x')),
+            'var3': xr.DataArray(data=data, dims=('y', 'x'), attrs={'coordinates': 'lon2 lat'}),
+            'var4': xr.DataArray(data=data, dims=('y', 'x'), attrs={'coordinates': 'not_exist lon lat'}),
             'lon': xr.DataArray(data=lon, dims=('y', 'x')),
+            'lon2': xr.DataArray(data=lon2, dims=('time', 'y', 'x')),
             'lat': xr.DataArray(data=lat, dims=('y', 'x'))
         }
 
@@ -642,6 +646,10 @@ def test_link_coords(self):
         self.assertNotIn('lon', datasets['var2'].coords)
         self.assertNotIn('lat', datasets['var2'].coords)
 
+        # The not existed dimension or coordinate should be dropped
+        self.assertNotIn('time', datasets['var3'].coords)
+        self.assertNotIn('not_exist', datasets['var4'].coords)
+
     def test_make_alt_coords_unique(self):
         """Test that created coordinate variables are unique."""
         import xarray as xr

satpy/writers/cf_writer.py

@@ -235,29 +235,30 @@ def assert_xy_unique(datas):
 
 
 def link_coords(datas):
-    """Link datasets and coordinates.
+    """Link dataarrays and coordinates.
 
-    If the `coordinates` attribute of a data array links to other datasets in the scene, for example
+    If the `coordinates` attribute of a data array links to other dataarrays in the scene, for example
     `coordinates='lon lat'`, add them as coordinates to the data array and drop that attribute. In the final call to
     `xr.Dataset.to_netcdf()` all coordinate relations will be resolved and the `coordinates` attributes be set
     automatically.
 
     """
-    for ds_name, dataset in datas.items():
-        coords = dataset.attrs.get('coordinates', [])
-        if isinstance(coords, str):
-            coords = coords.split(' ')
-        for coord in coords:
-            if coord not in dataset.coords:
+    for da_name, data in datas.items():
+        declared_coordinates = data.attrs.get('coordinates', [])
+        if isinstance(declared_coordinates, str):
+            declared_coordinates = declared_coordinates.split(' ')
+        for coord in declared_coordinates:
+            if coord not in data.coords:
                 try:
-                    dataset[coord] = datas[coord]
+                    dimensions_not_in_data = list(set(datas[coord].dims) - set(data.dims))
+                    data[coord] = datas[coord].squeeze(dimensions_not_in_data, drop=True)
                 except KeyError:
-                    warnings.warn('Coordinate "{}" referenced by dataset {} does not exist, dropping reference.'.format(
-                        coord, ds_name))
+                    warnings.warn('Coordinate "{}" referenced by dataarray {} does not exist, dropping reference.'
+                                  .format(coord, da_name))
                     continue
 
         # Drop 'coordinates' attribute in any case to avoid conflicts in xr.Dataset.to_netcdf()
-        dataset.attrs.pop('coordinates', None)
+        data.attrs.pop('coordinates', None)
 
 
 def dataset_is_projection_coords(dataset):