issues: 310819233

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id node_id number title user state locked assignee milestone comments created_at updated_at closed_at author_association active_lock_reason draft pull_request body reactions performed_via_github_app state_reason repo type
310819233 MDU6SXNzdWUzMTA4MTkyMzM= 2036 better error message for to_netcdf -> unlimited_dims 10194086 closed 0     4 2018-04-03T12:39:21Z 2018-05-18T14:48:32Z 2018-05-18T14:48:32Z MEMBER      

Code Sample, a copy-pastable example if possible

```python

Your code here

import numpy as np import xarray as xr x = np.arange(10) da = xr.Dataset(data_vars=dict(data=('dim1', x)), coords=dict(dim1=('dim1', x), dim2=('dim2', x))) da.to_netcdf('tst.nc', format='NETCDF4_CLASSIC', unlimited_dims='dim1')

```

Problem description

This creates the error RuntimeError: NetCDF: NC_UNLIMITED size already in use. With format='NETCDF4' silently creates the dimensions d, i, m, and \1.

The correct syntax is unlimited_dims=['dim1'].

With format='NETCDF4_CLASSIC' and unlimited_dims=['dim1', 'dim2'], still raises the not-so-helpful NC_UNLIMITED error.

I only tested with netCDF4 as backend.

Expected Output

  • better error message
  • work with unlimited_dims='dim1'

Output of xr.show_versions()

INSTALLED VERSIONS ------------------ commit: None python: 3.6.5.final.0 python-bits: 64 OS: Linux OS-release: 4.4.120-45-default machine: x86_64 processor: x86_64 byteorder: little LC_ALL: None LANG: en_GB.UTF-8 LOCALE: en_GB.UTF-8 xarray: 0.10.2 pandas: 0.22.0 numpy: 1.14.2 scipy: 1.0.1 netCDF4: 1.3.1 h5netcdf: 0.5.0 h5py: 2.7.1 Nio: None zarr: None bottleneck: 1.2.1 cyordereddict: 1.0.0 dask: 0.17.2 distributed: 1.21.5 matplotlib: 2.2.2 cartopy: 0.16.0 seaborn: 0.8.1 setuptools: 39.0.1 pip: 9.0.3 conda: None pytest: 3.5.0 IPython: 6.3.0 sphinx: 1.7.2 
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   completed 13221727 issue

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