import numpy as np import xarray as xr

Creates DataArrays

nt = 4 time = np.arange (nt) * 86400.0 time = xr.DataArray (time, coords=[time,], dims=["time",]) aa = time * 2.0

Adding attributes to DataArrays

time.attrs['units'] = "second" aa.attrs['units'] = "whatever"

Attributes are visible in the DataArrays

print ('----------> time DataArray: ') print (time) print ('----------> aa DataArray : ' ) print (aa) print ('----------> aa attributes : ') print (aa.attrs )

Creating a Dataset

ds = xr.Dataset( { "aa": (["time",], aa), }, coords={"time": (["time",], time), }, )

Attributes are not visible in the Dataset

print ('----------> DataSet before setting attributes') print (ds)

My request #1 : attributes of the DataArrays should be added to the DataSet (may be optional)

print ('----------> Attributes of aa in DataSet : none') print ( ds['aa'].attrs ) print ('----------> Attributes of aa outside DataSet : still here') print ( aa.attrs )

print ('----------> Attributes are not written to the NetCDF file') ds.to_netcdf ('sample1.nc')

Adding attributes directly to the Dataset

Attributes are still not visible in the Dataset

print ('----------> DataSet after setting attributes : attributes not shown' ) ds=ds.assign_attrs({'Visible':'NotInvisibleMan'}) ds['time'].attrs['units']="second" ds['aa'].attrs['units']="whatever"
ds.to_netcdf('safeReturn.nc') print(xr.open_dataset('safeReturn.nc').attrs) print(xr.open_dataset('safeReturn.nc')['aa'].attrs) print(xr.open_dataset('safeReturn.nc')['time'].attrs)