Set FillValue before reprojection

ndpyramid/core.py

@@ -1,10 +1,10 @@
 from __future__ import annotations  # noqa: F401
 
-import contextlib
 import typing
 from collections import defaultdict
 
 import datatree as dt
+import numpy as np
 import xarray as xr
 
 from .common import Projection
@@ -132,16 +132,13 @@ def pyramid_reproject(
         dst_transform = projection_model.transform(dim=dim)
 
         def reproject(da, var):
+            da.encoding['_FillValue'] = np.nan
             da = da.rio.reproject(
                 projection_model._crs,
                 resampling=Resampling[resampling_dict[var]],
                 shape=(dim, dim),
                 transform=dst_transform,
             )
-            da = da.where(da != da.rio.nodata)
-            with contextlib.suppress(KeyError):
-                del da.attrs['_FillValue']
-                del da.encoding['_FillValue']
             return da
 
         # create the data array for each level

tests/test_pyramids.py

@@ -41,7 +41,7 @@ def test_reprojected_pyramid_fill(temperature, benchmark):
     """
     pytest.importorskip('rioxarray')
     temperature = temperature.rio.write_crs('EPSG:4326')
-    pyramid = benchmark(lambda: pyramid_reproject(temperature, levels=2))
+    pyramid = benchmark(lambda: pyramid_reproject(temperature, levels=1))
     assert np.isnan(pyramid['0'].air.isel(time=0, x=0, y=0).values)