Keep attributes upon conservative regrid

Author: BSchilperoort

src/xarray_regrid/methods/conservative.py

@@ -79,6 +79,8 @@ def conservative_regrid_dataset(
     """Dataset implementation of the conservative regridding method."""
     data_vars: list[str] = list(data.data_vars)
     dataarrays = [data[var] for var in data_vars]
+    attrs = data.attrs
+    da_attrs = [da.attrs for da in dataarrays]
 
     for coord in coords:
         target_coords = coords[coord].to_numpy()
@@ -98,7 +100,11 @@ def conservative_regrid_dataset(
                 da = dataarrays[i].transpose(coord, ...)
                 dataarrays[i] = apply_weights(da, weights, coord, target_coords)
 
-    return xr.merge(dataarrays)  # TODO: add other coordinates/data variables back in.
+    for da, _attr in zip(dataarrays, da_attrs, strict=True):
+        da.attrs = _attr
+    regridded = xr.merge(dataarrays)
+    regridded.attrs = attrs
+    return regridded  # TODO: add other coordinates/data variables back in.
 
 
 def conservative_regrid_dataarray(
@@ -107,6 +113,7 @@ def conservative_regrid_dataarray(
     latitude_coord: str,
 ) -> xr.DataArray:
     """DataArray implementation of the conservative regridding method."""
+    attrs = data.attrs
     for coord in coords:
         if coord in data.coords:
             target_coords = coords[coord].to_numpy()
@@ -124,7 +131,7 @@ def conservative_regrid_dataarray(
 
             data = data.transpose(coord, ...)
             data = apply_weights(data, weights, coord, target_coords)
-
+    data.attrs = attrs
     return data
 
 

tests/test_most_common.py

@@ -82,9 +82,7 @@ def test_most_common(dummy_lc_data, dummy_target_grid):
 
 def test_attrs_dataarray(dummy_lc_data, dummy_target_grid):
     dummy_lc_data["lc"].attrs = {"test": "testing"}
-    da_regrid = dummy_lc_data["lc"].regrid.most_common(
-        dummy_target_grid
-    )
+    da_regrid = dummy_lc_data["lc"].regrid.most_common(dummy_target_grid)
     assert da_regrid.attrs != {}
     assert da_regrid.attrs == dummy_lc_data["lc"].attrs
 

tests/test_regrid.py

@@ -1,4 +1,3 @@
-from copy import deepcopy
 from pathlib import Path
 
 import pytest
@@ -150,3 +149,4 @@ def test_attrs_dataset_conservative(sample_input_data, sample_grid_ds):
         sample_grid_ds, latitude_coord="latitude"
     )
     assert ds_regrid.attrs == sample_input_data.attrs
+    assert ds_regrid["d2m"].attrs == sample_input_data["d2m"].attrs