No longer references DataArray where it shouldn't, so that things work again without xarray installed. Fixes #15

src/wrf/decorators.py

@@ -186,26 +186,29 @@ def left_iteration(ref_var_expected_dims,
             # Skip the possible empty/missing arrays for the join method
             skip_missing = False
             for arg in new_args:
-                if isinstance(arg, DataArray):
-                    arr = to_np(arg)
-                elif isinstance(arg, np.ndarray):
-                    arr = arg
+                try:
+                    _ = arg.ndim
+                except AttributeError:
+                    continue # Not an array object
                 else:
-                    continue
-                
-                if isinstance(arr, np.ma.MaskedArray):
-                    if arr.mask.all():
+                    arr = to_np(arg)
                 
+                try:
+                    all_masked = arr.mask.all()
+                except AttributeError:
+                    pass # Not a masked array
+                else:
+                    if all_masked:
                         for output in viewvalues(outd):
                             output[left_and_slice_idxs] = (
                                 Constants.DEFAULT_FILL)
                         skip_missing = True
                         mask_output = True
+                        break
             
             if skip_missing:
                 continue
             
-            
             # Insert the output views if one hasn't been provided
             if "outview" not in new_kargs:
                 for outkey,output in viewitems(outd):

src/wrf/specialdec.py

@@ -70,12 +70,8 @@ def uvmet_left_iter(alg_dtype=np.float64):
                 mode = 2 # probably 3D with 2D lat/lon plus Time
         
         has_missing = False
-        u_arr = u
-        if isinstance(u, DataArray):
         u_arr = to_np(u)
             
-        v_arr = v
-        if isinstance(v, DataArray):
         v_arr = to_np(v)
           
         umissing = Constants.DEFAULT_FILL