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
33833155,MDU6SXNzdWUzMzgzMzE1NQ==,136,More consistent datetime conversion,1217238,closed,0,,836999,0,2014-05-19T20:16:32Z,2014-12-19T20:54:51Z,2014-12-19T05:27:50Z,MEMBER,,,,"Todo:
- [x] Decide on rules for datetime conversion
- [x] Implement them
- [ ] Document them

Currently:
- All `np.datetime64` arrays or objects are converted to ns precision
- We leave other datetime or datetime-like objects intact in numpy arrays of dtype=object.

Arguably, we should convert everything to `'datetime64[ns]'`, if possible. This is the approach we now take for decoding NetCDF time variables (#126).

Reference discussion: #134. From @akleeman:

> In #125 I went the route of forcing datetimes to be datetime64[ns]. This is probably part of a broader conversation, but doing so might save some future headaches. Of course ... it would also restrict us to nanosecond precision. Basically I feel like we should either force datetimes to be datetime64[ns] or make sure that operations on datetime objects preserve their type.
> 
> Probably worth getting this in and picking that conversation back up if needed. In which case could you add tests which make sure variables with datetime objects are still datetime objects after concatenation? If those start getting cast to datetime[ns] it'll start get confusing for users.
> 
> Also worth considering: how should datetime64[us] datetimes be handled? Currently they get cast to [ns] which, since datetimes do not, could get confusing.
","{""url"": ""https://api.github.com/repos/pydata/xarray/issues/136/reactions"", ""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,completed,13221727,issue
49478188,MDU6SXNzdWU0OTQ3ODE4OA==,279,BUG: reindex method creates new dims/coords,4194485,closed,0,,836999,0,2014-11-20T01:29:21Z,2014-12-19T07:21:31Z,2014-12-19T07:21:31Z,NONE,,,,"If you reindex an xray dataset or dataarray with a coordinate with a different name, an extra dimension and coordinate is added to the xray object (with the name of the reindexing coordinate). Here's a simple example:

```
x1 = xray.DataArray(np.random.randn(5, 6, 7), dims=[""lon"", ""lat"", ""time""])
time2 = xray.DataArray([1, 3], dims=""time2"")
x2 = x1.reindex(time=time2)
```

x2 now has coordinates ""time"" and ""time2"".

I'm using xray version 0.3.1-4-gee1369f.
","{""url"": ""https://api.github.com/repos/pydata/xarray/issues/279/reactions"", ""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,completed,13221727,issue