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
128528319,MDU6SXNzdWUxMjg1MjgzMTk=,722,All dimmensions become coordinates?,242610,closed,0,,,4,2016-01-25T12:39:57Z,2016-12-29T01:12:16Z,2016-12-29T01:12:16Z,NONE,,,,"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?
","{""url"": ""https://api.github.com/repos/pydata/xarray/issues/722/reactions"", ""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,completed,13221727,issue
129843955,MDU6SXNzdWUxMjk4NDM5NTU=,734,Coords that look like ranges are not written in netcdf files.,242610,closed,0,,,1,2016-01-29T18:21:02Z,2016-01-30T01:04:26Z,2016-01-30T01:04:26Z,NONE,,,,"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`.
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