accept variable with no "dimensions" key as dimensionless

Author: mhidas

ncwriter/template.py

@@ -281,7 +281,7 @@ def create_variables(self, **kwargs):
         """
         for varname, var in self.variables.items():
             datatype = var['type']
-            dimensions = var['dimensions']
+            dimensions = var.get('dimensions')
             cwargs = kwargs.copy()
             if dimensions is None:  # no kwargs in createVariable
                 ncvar = self.ncobj.createVariable(varname, datatype)

test_ncwriter/test_template.py

@@ -231,6 +231,12 @@ def test_close_file_on_exception(self):
         self.assertRaises(ValueError, template.to_netcdf, self.temp_nc_file)
         self.assertFalse(template.ncobj.isopen())
 
+    def test_dimensionless_variable(self):
+        template = DatasetTemplate(variables={'X': {'type': 'double', 'data': None}})
+        template.to_netcdf(self.temp_nc_file)
+
+        dataset = Dataset(self.temp_nc_file)
+        self.assertEqual((), dataset.variables['X'].dimensions)
 
 # TODO: add data from multiple numpy arrays
 # e.g. template.add_data(TIME=time_values, TEMP=temp_values, PRES=pres_values)