html_url,issue_url,id,node_id,user,created_at,updated_at,author_association,body,reactions,performed_via_github_app,issue
https://github.com/pydata/xarray/issues/5510#issuecomment-866314326,https://api.github.com/repos/pydata/xarray/issues/5510,866314326,MDEyOklzc3VlQ29tbWVudDg2NjMxNDMyNg==,22566757,2021-06-22T20:33:44Z,2021-06-22T20:37:53Z,CONTRIBUTOR,"~`encoding` is where that information is stored between reading a dataset in from disk and saving it back out again.~ `_encode_coordinates` can take a default value from either of `encoding` or `attrs`, but a falsy value will be overwritten.  Setting `.attrs[""coordinates""] = "" ""` should work.

```python
>>> import numpy as np, xarray as xr
>>> data = xr.DataArray(np.random.randn(2, 3), dims=(""x"", ""y""), coords={""x"": [10, 20]})
>>> ds = xr.Dataset({""foo"": data, ""bar"": (""x"", [1, 2]), ""fake"": 10})
>>> ds = ds.assign_coords({""reftime"":np.array(""2004-11-01T00:00:00"", dtype=np.datetime64)})
>>> ds = ds.assign({""test"": 1})
>>> ds.test.encoding[""coordinates""] = "" ""
>>> ds.to_netcdf(""file.nc"")
```
```bash
$ ncdump -h file.nc
netcdf file {
dimensions:
        x = 2 ;
        y = 3 ;
variables:
        int64 x(x) ;
        double foo(x, y) ;
                foo:_FillValue = NaN ;
                foo:coordinates = ""reftime"" ;
        int64 bar(x) ;
                bar:coordinates = ""reftime"" ;
        int64 fake ;
                fake:coordinates = ""reftime"" ;
        int64 reftime ;
                reftime:units = ""days since 2004-11-01 00:00:00"" ;
                reftime:calendar = ""proleptic_gregorian"" ;
        int64 test ;
                test:coordinates = "" "" ;
}
```
As mentioned above, the XArray data model associates coordinates with dimensions rather than with variables, so any time you read the dataset back in again, the `test` variable will gain `reftime` as a coordinate, because the dimensions of `reftime` (`()`), are a subset of the dimensions of `test` (also `()`).

Not producing a `coordinates` attribute for variables mentioned in another variable's `bounds` attribute (or a few other attributes, for that matter) would be entirely doable within the function linked above, and should be straightforward if you want to make a PR for that.

Making `realization` and the bounds show up in `ds.coords` rather than `ds.data_vars` may also skip setting the `coordinates` attribute, though I'm less sure of that.  It would, however, add `realization` to the `coordinates` attributes of every other `data_var` unless you overrode that, which may not be what you want.","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,927336712
https://github.com/pydata/xarray/issues/5510#issuecomment-866175750,https://api.github.com/repos/pydata/xarray/issues/5510,866175750,MDEyOklzc3VlQ29tbWVudDg2NjE3NTc1MA==,2448579,2021-06-22T17:14:34Z,2021-06-22T17:14:34Z,MEMBER,This is the function to look at if you wanted to fix it: https://github.com/pydata/xarray/blob/1f5c63379e1a3e803515f467d9dcc0c9f7b1a0db/xarray/conventions.py#L707,"{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,927336712
https://github.com/pydata/xarray/issues/5510#issuecomment-866116219,https://api.github.com/repos/pydata/xarray/issues/5510,866116219,MDEyOklzc3VlQ29tbWVudDg2NjExNjIxOQ==,5635139,2021-06-22T16:00:52Z,2021-06-22T16:48:24Z,MEMBER,"Coords are on the dataset rather than the variable, so it requires something like `ds = ds.reset_coords()`

Thanks for the clear example!","{""total_count"": 1, ""+1"": 1, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,927336712
https://github.com/pydata/xarray/issues/5510#issuecomment-866140391,https://api.github.com/repos/pydata/xarray/issues/5510,866140391,MDEyOklzc3VlQ29tbWVudDg2NjE0MDM5MQ==,40183561,2021-06-22T16:28:56Z,2021-06-22T16:29:32Z,CONTRIBUTOR,"@dcherian thanks! I've tried overriding with `.attrs[""coordinates""] = None`, `.attrs[""coordinates""] = """"` and `.attrs[""coordinates""] = False` but that doesn't seem to work either. Would be great if that worked and would solve my problem!","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,927336712
https://github.com/pydata/xarray/issues/5510#issuecomment-866121561,https://api.github.com/repos/pydata/xarray/issues/5510,866121561,MDEyOklzc3VlQ29tbWVudDg2NjEyMTU2MQ==,2448579,2021-06-22T16:07:27Z,2021-06-22T16:08:35Z,MEMBER,"I am not sure there is a good solution here.

As @max-sixty says, xarray does not carry around information that links a specific variable to a subset of coordinate variables (like a coordinates attribute). So in effect, all variables are associated with all coordinate variables.

We could special-case bounds variables (we do this in some places in the encoding/decoding functions) but `realization` will always be a problem. I think you can override it by explicitly setting the `coordinates=""""` attribute. Perhaps `.attrs[""coordinates""] = None` will avoid writing the attribute, if not we could make it work?

cc @DWesl ","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,927336712