# Xarray to netcdf (ValueError: The truth value of an array with more than one element is ambiguous. Use a.any() or a.all()) **URL:** \ **Category:** General\ **Created:** [December 7, 2022, 12:17pm UTC](https://openradar.discourse.group/t/xarray-to-netcdf-valueerror-the-truth-value-of-an-array-with-more-than-one-element-is-ambiguous-use-a-any-or-a-all/114 "2022-12-07T12:17:56Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![SandeepAllampalli](https://yyz2.discourse-cdn.com/free1/user_avatar/openradar.discourse.group/sandeepallampalli/32/17_2.png) [@SandeepAllampalli](https://openradar.discourse.group/u/SandeepAllampalli)\ **Post date:** [December 7, 2022, 12:17pm UTC](https://openradar.discourse.group/t/xarray-to-netcdf-valueerror-the-truth-value-of-an-array-with-more-than-one-element-is-ambiguous-use-a-any-or-a-all/114/1 "2022-12-07T12:17:56Z")
Hello People, Does anyone come across this type of problem while saving xarray dataset to netcdf file? ```auto Dimensions: (time: 17518, y: 900, x: 900) Coordinates: * time (time) datetime64[ns] 2006-01-01T00:45:00 ... 2021-12-31T23:50:00 * y (y) float64 -4.658e+06 -4.657e+06 ... -3.76e+06 -3.759e+06 * x (x) float64 -5.23e+05 -5.22e+05 -5.21e+05 ... 3.75e+05 3.76e+05 Data variables: RW (time, y, x) float32 dask.array Attributes: radarid: 10000 formatversion: 2 radolanversion: 01.01.00 radarlocations: ['bln', 'drs', 'eis', 'emd', 'ess', 'fbg', 'fld', 'fra',... ``` When I tried to save xarray dataset to netcdf like below. I get the following error. ```auto ds.to_netcdf("D:/Sandeep/Thesis/Data/dsM.nc") ``` Error: ```auto ds.to_netcdf("D:/Sandeep/Thesis/Data/dsM.nc", engine="h5netcdf", invalid_netcdf=True) Traceback (most recent call last): File "C:\Users\Admin\AppData\Local\Temp\ipykernel_7676\1512561570.py", line 1, in ds.to_netcdf("D:/Sandeep/Thesis/Data/dsM.nc", engine="h5netcdf", invalid_netcdf=True) File "C:\Users\Admin\anaconda3\envs\wradlib\lib\site-packages\xarray\core\dataset.py", line 1899, in to_netcdf return to_netcdf( # type: ignore # mypy cannot resolve the overloads:( File "C:\Users\Admin\anaconda3\envs\wradlib\lib\site-packages\xarray\backends\api.py", line 1230, in to_netcdf dump_to_store( File "C:\Users\Admin\anaconda3\envs\wradlib\lib\site-packages\xarray\backends\api.py", line 1277, in dump_to_store store.store(variables, attrs, check_encoding, writer, unlimited_dims=unlimited_dims) File "C:\Users\Admin\anaconda3\envs\wradlib\lib\site-packages\xarray\backends\common.py", line 266, in store variables, attributes = self.encode(variables, attributes) File "C:\Users\Admin\anaconda3\envs\wradlib\lib\site-packages\xarray\backends\common.py", line 355, in encode variables, attributes = cf_encoder(variables, attributes) File "C:\Users\Admin\anaconda3\envs\wradlib\lib\site-packages\xarray\conventions.py", line 868, in cf_encoder new_vars = {k: encode_cf_variable(v, name=k) for k, v in variables.items()} File "C:\Users\Admin\anaconda3\envs\wradlib\lib\site-packages\xarray\conventions.py", line 868, in new_vars = {k: encode_cf_variable(v, name=k) for k, v in variables.items()} File "C:\Users\Admin\anaconda3\envs\wradlib\lib\site-packages\xarray\conventions.py", line 273, in encode_cf_variable var = coder.encode(var, name=name) File "C:\Users\Admin\anaconda3\envs\wradlib\lib\site-packages\xarray\coding\variables.py", line 169, in encode if not pd.isnull(fill_value): ValueError: The truth value of an array with more than one element is ambiguous. Use a.any() or a.all() ds.RW.to_netcdf("D:/Sandeep/Thesis/Data/dsM.nc", engine="h5netcdf", invalid_netcdf=True) Traceback (most recent call last): File "C:\Users\Admin\AppData\Local\Temp\ipykernel_7676\1590374310.py", line 1, in ds.RW.to_netcdf("D:/Sandeep/Thesis/Data/dsM.nc", engine="h5netcdf", invalid_netcdf=True) File "C:\Users\Admin\anaconda3\envs\wradlib\lib\site-packages\xarray\core\dataarray.py", line 3752, in to_netcdf return to_netcdf( # type: ignore # mypy cannot resolve the overloads:( File "C:\Users\Admin\anaconda3\envs\wradlib\lib\site-packages\xarray\backends\api.py", line 1230, in to_netcdf dump_to_store( File "C:\Users\Admin\anaconda3\envs\wradlib\lib\site-packages\xarray\backends\api.py", line 1277, in dump_to_store store.store(variables, attrs, check_encoding, writer, unlimited_dims=unlimited_dims) File "C:\Users\Admin\anaconda3\envs\wradlib\lib\site-packages\xarray\backends\common.py", line 266, in store variables, attributes = self.encode(variables, attributes) File "C:\Users\Admin\anaconda3\envs\wradlib\lib\site-packages\xarray\backends\common.py", line 355, in encode variables, attributes = cf_encoder(variables, attributes) File "C:\Users\Admin\anaconda3\envs\wradlib\lib\site-packages\xarray\conventions.py", line 868, in cf_encoder new_vars = {k: encode_cf_variable(v, name=k) for k, v in variables.items()} File "C:\Users\Admin\anaconda3\envs\wradlib\lib\site-packages\xarray\conventions.py", line 868, in new_vars = {k: encode_cf_variable(v, name=k) for k, v in variables.items()} File "C:\Users\Admin\anaconda3\envs\wradlib\lib\site-packages\xarray\conventions.py", line 273, in encode_cf_variable var = coder.encode(var, name=name) File "C:\Users\Admin\anaconda3\envs\wradlib\lib\site-packages\xarray\coding\variables.py", line 169, in encode if not pd.isnull(fill_value): ValueError: The truth value of an array with more than one element is ambiguous. Use a.any() or a.all() ds['RW'][0].plot() Out[46]: ds Out[47]: Dimensions: (time: 17518, y: 900, x: 900) Coordinates: * time (time) datetime64[ns] 2006-01-01T00:45:00 ... 2021-12-31T23:50:00 * y (y) float64 -4.658e+06 -4.657e+06 ... -3.76e+06 -3.759e+06 * x (x) float64 -5.23e+05 -5.22e+05 -5.21e+05 ... 3.75e+05 3.76e+05 Data variables: RW (time, y, x) float32 dask.array Attributes: radarid: 10000 formatversion: 2 radolanversion: 01.01.00 radarlocations: ['bln', 'drs', 'eis', 'emd', 'ess', 'fbg', 'fld', 'fra',... ds.to_netcdf("D:/Sandeep/Thesis/Data/dsM.nc") Traceback (most recent call last): File "C:\Users\Admin\AppData\Local\Temp\ipykernel_7676\2740476879.py", line 1, in ds.to_netcdf("D:/Sandeep/Thesis/Data/dsM.nc") File "C:\Users\Admin\anaconda3\envs\wradlib\lib\site-packages\xarray\core\dataset.py", line 1899, in to_netcdf return to_netcdf( # type: ignore # mypy cannot resolve the overloads:( File "C:\Users\Admin\anaconda3\envs\wradlib\lib\site-packages\xarray\backends\api.py", line 1230, in to_netcdf dump_to_store( File "C:\Users\Admin\anaconda3\envs\wradlib\lib\site-packages\xarray\backends\api.py", line 1277, in dump_to_store store.store(variables, attrs, check_encoding, writer, unlimited_dims=unlimited_dims) File "C:\Users\Admin\anaconda3\envs\wradlib\lib\site-packages\xarray\backends\common.py", line 266, in store variables, attributes = self.encode(variables, attributes) File "C:\Users\Admin\anaconda3\envs\wradlib\lib\site-packages\xarray\backends\common.py", line 355, in encode variables, attributes = cf_encoder(variables, attributes) File "C:\Users\Admin\anaconda3\envs\wradlib\lib\site-packages\xarray\conventions.py", line 868, in cf_encoder new_vars = {k: encode_cf_variable(v, name=k) for k, v in variables.items()} File "C:\Users\Admin\anaconda3\envs\wradlib\lib\site-packages\xarray\conventions.py", line 868, in new_vars = {k: encode_cf_variable(v, name=k) for k, v in variables.items()} File "C:\Users\Admin\anaconda3\envs\wradlib\lib\site-packages\xarray\conventions.py", line 273, in encode_cf_variable var = coder.encode(var, name=name) File "C:\Users\Admin\anaconda3\envs\wradlib\lib\site-packages\xarray\coding\variables.py", line 169, in encode if not pd.isnull(fill_value): ValueError: The truth value of an array with more than one element is ambiguous. Use a.any() or a.all() ``` ---
**Author:** ![kmuehlbauer](https://yyz2.discourse-cdn.com/free1/user_avatar/openradar.discourse.group/kmuehlbauer/32/439_2.png) [@kmuehlbauer](https://openradar.discourse.group/u/kmuehlbauer)\ **Post date:** [December 8, 2022, 8:40am UTC](https://openradar.discourse.group/t/xarray-to-netcdf-valueerror-the-truth-value-of-an-array-with-more-than-one-element-is-ambiguous-use-a-any-or-a-all/114/2 "2022-12-08T08:40:17Z")
Could you please have a look at the contents of `ds.RW.encoding`? As the RADOLAN data has three values for `_FillValue` (which get mapped to `NaN`) this is OK for reading, but not for writing. You would need to only keep one of those `_FillValue`. ---
**Author:** ![SandeepAllampalli](https://yyz2.discourse-cdn.com/free1/user_avatar/openradar.discourse.group/sandeepallampalli/32/17_2.png) [@SandeepAllampalli](https://openradar.discourse.group/u/SandeepAllampalli)\ **Post date:** [December 8, 2022, 10:43am UTC](https://openradar.discourse.group/t/xarray-to-netcdf-valueerror-the-truth-value-of-an-array-with-more-than-one-element-is-ambiguous-use-a-any-or-a-all/114/3 "2022-12-08T10:43:30Z")
```auto ds.RW.encoding Out[149]: {'source': 'D:\\Sandeep\\Thesis\\Data\\BIN\\Extracted\\raa01-rw_10000-0601010050-dwd---bin.gz', '_FillValue': array([2490, 2500, 65535]), 'scale_factor': 0.1, 'add_offset': 0.0, 'dtype': dtype('uint16'), 'coordinates': 'time y x'} ``` ---
**Author:** ![mgrover1](https://yyz2.discourse-cdn.com/free1/user_avatar/openradar.discourse.group/mgrover1/32/7_2.png) [@mgrover1](https://openradar.discourse.group/u/mgrover1)\ **Post date:** [December 8, 2022, 3:48pm UTC](https://openradar.discourse.group/t/xarray-to-netcdf-valueerror-the-truth-value-of-an-array-with-more-than-one-element-is-ambiguous-use-a-any-or-a-all/114/4 "2022-12-08T15:48:03Z")
You would want to only use one of those fill values instead of all three. For example, ```python ds.encoding['_FillValue'] = ds.encoding._FillValue[:1] ``` ---
**Author:** ![kmuehlbauer](https://yyz2.discourse-cdn.com/free1/user_avatar/openradar.discourse.group/kmuehlbauer/32/439_2.png) [@kmuehlbauer](https://openradar.discourse.group/u/kmuehlbauer)\ **Post date:** [December 9, 2022, 8:57am UTC](https://openradar.discourse.group/t/xarray-to-netcdf-valueerror-the-truth-value-of-an-array-with-more-than-one-element-is-ambiguous-use-a-any-or-a-all/114/5 "2022-12-09T08:57:48Z")
I’d propably pick `65535` in that case. But that’s just my personal view.