Clear c_grid_axis_shift from attrs when destaggering (#106)

Co-authored-by: Anderson Banihirwe <[email protected]>

tests/test_accessors.py

@@ -108,10 +108,11 @@ def test_dataarray_destagger_with_postprocess(test_grid):
     # Check staggered to unstaggered dimension coordinate handling
     xr.testing.assert_allclose(destaggered['x'], postprocessed['x'])
 
-    # Check attributes are preserved
+    # Check attributes are preserved, other than those made invalid by destaggering
     assert set(destaggered.attrs.keys()) == set(data.attrs.keys()) - {
         'stagger',
     }
+    assert 'c_grid_axis_shift' not in destaggered['x'].attrs
 
 
 @pytest.mark.parametrize('test_grid', ['lambert_conformal', 'mercator'], indirect=True)

xwrf/destagger.py

@@ -69,7 +69,7 @@ def _destag_variable(datavar, stagger_dim=None, unstag_dim_name=None):
     return xr.Variable(
         dims=tuple(str(unstag_dim_name) if dim == stagger_dim else dim for dim in center_mean.dims),
         data=center_mean.data,
-        attrs=_drop_attrs(datavar.attrs, ('stagger',)),
+        attrs=_drop_attrs(datavar.attrs, ('stagger', 'c_grid_axis_shift')),
         encoding=datavar.encoding,
         fastpath=True,
     )