Merge dataset after being converted from numpy.array to data array with attributes

Question

I am trying to save some variables as a netCDF file. I am taking these steps to do it.

   plev =  xr.DataArray(plev,coords=[levels,lat,lon], dims=["lev","lat","lon"])

    U_v32 = xr.DataArray(U_v32,coords=[levels,lat,lon], dims=["lev","lat","lon"]), 
    attrs=dict(long_name = "eastward_wind" , standard_name = "eastward_wind" , units = "m s-1" , 
        valid_range = "-1.e+15f, 1.e+15f" , vmax = "1.e+15f" , vmin = "-1.e+15f" , coordinates = "lon lat" ,)

Where plev is:

<xarray.DataArray (lev: 32, lat: 192, lon: 288)>
array([[[3.64346569e+00, 3.64346569e+00, 3.64346569e+00, ...,

Coordinates:
  * lev      (lev) int64 1 2 3 4 5 6 7 8 9 10 ... 23 24 25 26 27 28 29 30 31 32
  * lat      (lat) float64 -90.0 -89.06 -88.12 -87.17 ... 87.17 88.11 89.06 90.0
  * lon      (lon) float64 0.0 1.25 2.5 3.75 5.0 ... 355.0 356.2 357.5 358.8

And U_v32 is:

(<xarray.DataArray (lev: 32, lat: 192, lon: 288)>
array([[[-1.12275551e-01, -1.67688605e-01, -2.23421148e-01, ...,
          7.19201197e-02,  6.93718333e-03, -5.42723485e-02],
        [ 4.28133062e+00,  4.01246378e+00,  3.74175282e+00, ...,
          5.00617035e+00,  4.76159409e+00,  4.51793771e+00],
        [ 6.71847498e+00,  6.23453015e+00,  5.75207444e+00, ...,
          8.12475620e+00,  7.66082277e+00,  7.19229493e+00],
        ...,

Coordinates:
  * lev      (lev) int64 1 2 3 4 5 6 7 8 9 10 ... 23 24 25 26 27 28 29 30 31 32
  * lat      (lat) float64 -90.0 -89.06 -88.12 -87.17 ... 87.17 88.11 89.06 90.0
  * lon      (lon) float64 0.0 1.25 2.5 3.75 5.0 ... 355.0 356.2 357.5 358.8,)

Then I do:

    plev = plev.to_dataset(name="plev")
    U_v32 = U_v32.to_dataset(name = 'U')

And finally merge those and then save as netCDF:

    data_v32 = xr.merge([U_v32,plev]) 

    data_v32.to_netcdf(data_v32_final.nc4)

But I got this error before the variables should be merged:

    U_v32 = U_v32.to_dataset(name = 'U')
AttributeError: 'tuple' object has no attribute 'to_dataset'

Is because I defined the attributes for that variable as a dictionary?. Is there a way to not have this error?.

Thanks in advance

nuvolet · Accepted Answer · 2023-07-06 21:19:49Z

0

I looked closely when defined the dataArray and I found what was the problem, basically I had to include the attrs inside the xr.DataArray. It was defined out of it:

   U_v32 = xr.DataArray(U_v32,coords=[levels,lat,lon], dims=["lev","lat","lon"], 
    attrs=dict(long_name = "eastward_wind" , standard_name = "eastward_wind" , units = "m s-1" , 
        valid_range = "-1.e+15f, 1.e+15f" , vmax = "1.e+15f" , vmin = "-1.e+15f" , coordinates = "lon lat" ,))

Then the conversion to dataset and merging work fine and I can save the variables as netCDF

answered Jul 6, 2023 at 21:19

nuvolet

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