earthkit xarray engine sel() issue

[jeffbask7]

Selecting coordinates using ds.sel(latitude=y, longitude=x, method='nearest') returns empty data arrays using the earthkit engine. to_xarray(engine = 'cfgrib') does not have this issue. Is this a potential bug?

[sandorkertesz]

Thank you for reporting this issue. For my test case it works. How did you generate ds? Can you share the input data with me?

[jeffbask7]

import earthkit as ekt
ds = ekt.data.from_source("ecmwf-open-data",
source='aws',
model='ifs',
param=["2t"],
step=[24],
)
ds_xr_earthkit = ds.to_xarray()
ds_xr_cfgrib = ds.to_xarray(engine='cfgrib')

nearest_value_cfgrib = (ds_xr_cfgrib['t2m'].sel(latitude=35, longitude=-90, method='nearest').item())
nearest_value_earthkit = (ds_xr_earthkit['2t'].sel(latitude=35, longitude=-90, method='nearest').item())

nearest_value_cfgrib is returned as a single value as expected. nearest_value_earthkit generates error due to (ds_xr_earthkit['2t'].sel(latitude=35, longitude=-90, method='nearest').item()) having no value.

[sandorkertesz]

Thank you for the reply. I can confirm it is a bug and it happens when there is only a single field in the input. If I use e.g. step=[24,36] then

ds_xr_earthkit['2t'].sel(latitude=35, longitude=-90, method='nearest').values

works.
The fix will be available in a hotfix release.