issues

I have a netcdf file that looks like this (ncdump):

``` netcdf filevYpcG2 { dimensions: coor1 = 2 ; dim1 = 2 ; variables: int coor1(coor1) ; coor1:_FillValue = 999999 ; int var1(coor1) ; var1:_FillValue = 999999 ; int var2(dim1) ; var2:units = "unit1" ; var2:_FillValue = 999999 ; var2:attr_name = "variable1" ;

// global attributes: :metadata1 = "metadata1" ; data:

coor1 = 1, 2 ;

var1 = 1, 2 ;

var2 = 3, 4 ; } ```

When opening it in xray (xarray) I therefore expect dim1 to be a dimension and coor1 to be a coordinate, because coor1 is also a variable, coor1(coor1)? But when opening the dataset in xray, I get the following:

``` In [1]: import xray;

In [2]: filename = "/tmp/filevYpcG2"

In [3]: x = xray.open_dataset(filename)

In [4]: x Out[4]: <xray.Dataset> Dimensions: (coor1: 2, dim1: 2) Coordinates: * coor1 (coor1) float64 1.0 2.0 * dim1 (dim1) int64 0 1 Data variables: var1 (coor1) float64 1.0 2.0 var2 (dim1) float64 3.0 4.0 Attributes: metadata1: metadata1

In [5]: x.coords Out[5]: Coordinates: * coor1 (coor1) float64 1.0 2.0 * dim1 (dim1) int64 0 1

In [6]: x.dims Out[6]: Frozen(SortedKeysDict({u'coor1': 2, u'dim1': 2}))

In [7]: x.data_vars Out[7]: Data variables: var1 (coor1) float64 1.0 2.0 var2 (dim1) float64 3.0 4.0 ```

That is, both coor1 and dim1 becomes coordinate variables. I expected only coor1 to become a coordinate variable, and not dim1.

Am I wrohg, or is it meant to be like this?

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.