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/1380#issuecomment-296274069,https://api.github.com/repos/pydata/xarray/issues/1380,296274069,MDEyOklzc3VlQ29tbWVudDI5NjI3NDA2OQ==,8699967,2017-04-21T18:49:57Z,2017-04-21T19:44:00Z,CONTRIBUTOR,"Thank you @spencerahill and @shoyer. That was brilliant.

Here is the solution:
```python
path_to_files = '*.grib2'
def extract_date(ds):
    for var in ds.variables:
        if 'initial_time' in ds[var].attrs.keys():
            grid_time = pd.to_datetime(ds[var].attrs['initial_time'],
                                       format=""%m/%d/%Y (%H:%M)"")
            if 'forecast_time' in ds[var].attrs.keys():
                time_units = 'h'
                if 'forecast_time_units' in ds[var].attrs.keys():
                    time_units =  str(ds[var].attrs['forecast_time_units'][0])
                grid_time += np.timedelta64(int(ds[var].attrs['forecast_time'][0]),
                                            time_units)

            return ds.assign(time=grid_time)
    raise ValueError(""Time attribute missing: {0}"".format(self.search_time_attr))

with xr.open_mfdataset(path_to_files,
                       concat_dim='time',
                       preprocess=extract_date,
                       engine='pynio') as xd:
    print(xd)
```","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,223440405
https://github.com/pydata/xarray/issues/1380#issuecomment-296260389,https://api.github.com/repos/pydata/xarray/issues/1380,296260389,MDEyOklzc3VlQ29tbWVudDI5NjI2MDM4OQ==,1217238,2017-04-21T17:57:07Z,2017-04-21T17:57:07Z,MEMBER,You can use the `preprocess` argument to `open_mfdataset` to create a new dimension from the attribute value.,"{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,223440405
https://github.com/pydata/xarray/issues/1380#issuecomment-296253682,https://api.github.com/repos/pydata/xarray/issues/1380,296253682,MDEyOklzc3VlQ29tbWVudDI5NjI1MzY4Mg==,6200806,2017-04-21T17:29:30Z,2017-04-21T17:29:30Z,CONTRIBUTOR,"open_mfdataset has a 'concat_dim' optional keyword argument where you can specify the name of a new dimension that you want to concatenate your files over.  You can read more about this in the [API reference on open_mfdataset](http://xarray.pydata.org/en/stable/generated/xarray.open_mfdataset.html#xarray.open_mfdataset).

You could then overwrite the coordinate of that new dimension with your desired time coordinate.
Does that help?","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,223440405