Coords that look like ranges are not written in netcdf files.

[wilhelmsen]

This may be related to #733, but I am not sure, so I create a new one to keep it clean. It was discovered when creating the second example for #722 .

When the coords from #722 are changed to coords=[np.array([0, 1], np.int64)], they are not written to the netcdf file.

Example:

In [1]: import xray as xr

In [2]: import numpy as np

In [3]: var1 = xr.DataArray(np.array([1, 2], np.float64), coords=[np.array([0, 1], np.int64)], dims=["coor1",], name = "var1")

In [4]: var2 = xr.DataArray(np.array([3, 4], np.float64), dims=["dim1",], name = "var2")

In [5]: ds = xr.Dataset({"var1": var1, "var2": var2})

In [6]: ds
Out[6]: 
<xray.Dataset>
Dimensions:  (coor1: 2, dim1: 2)
Coordinates:
  * coor1    (coor1) int64 0 1
  * dim1     (dim1) int64 0 1
Data variables:
    var1     (coor1) float64 1.0 2.0
    var2     (dim1) float64 3.0 4.0

In [7]:  ds.to_netcdf("/tmp/from_xr_2.nc")

And then, no coor1 data variable in the file:

$ ncdump /tmp/from_xr_2.nc
netcdf from_xr_2 {
dimensions:
    coor1 = 2 ;
    dim1 = 2 ;
variables:
    double var1(coor1) ;
    double var2(dim1) ;
data:

 var1 = 1, 2 ;

 var2 = 3, 4 ;
}

Change it back:

In [8]: var1 = xr.DataArray(np.array([1, 2], np.float64), coords=[np.array([1, 2], np.int64)], dims=["coor1",], name = "var1")

In [9]: ds = xr.Dataset({"var1": var1, "var2": var2})

In [10]: ds.to_netcdf("/tmp/from_xr_3.nc")

and coor1 is back in the file:

$ ncdump /tmp/from_xr_3.nc
netcdf from_xr_3 {
dimensions:
    coor1 = 2 ;
    dim1 = 2 ;
variables:
    int64 coor1(coor1) ;
    double var1(coor1) ;
    double var2(dim1) ;
data:

 coor1 = 1, 2 ;

 var1 = 1, 2 ;

 var2 = 3, 4 ;
}

That is, when the coords seem like they are similar to a range.

[shoyer]

Yep, this is exactly the same issue as #733... closing this in favor of that issue