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/2007#issuecomment-375828864,https://api.github.com/repos/pydata/xarray/issues/2007,375828864,MDEyOklzc3VlQ29tbWVudDM3NTgyODg2NA==,6815844,2018-03-24T00:05:08Z,2018-03-24T00:05:08Z,MEMBER,"> I don't think the kwarg should be called fill_value - that traditionally has a specific meaning of ""the value to replace NaN with"". 

Agreed. [`dask.ghost`](http://dask.pydata.org/en/latest/array-ghost.html#boundaries) has `boundaries` keyword, for which we can choose between *periodic*, *reflect*, and any constant.
I think this would be a good reference.
Maybe we can deprecate `fill_value` keyword and replace it by `boundaries`?
(I slightly regret that I choose `fill_value` keyword in `construct`).

> How it's implemented - do you have a view here? 

Only a slight modification of `construct` machinery realizes this (see #2011).
I think this option should be available only in `construct` method (not in the traditional rolling constructor) for the sake of simplicity (according to this [comment](https://github.com/pydata/xarray/issues/2010#issuecomment-375750884)).","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,307783090
https://github.com/pydata/xarray/issues/2007#issuecomment-375681041,https://api.github.com/repos/pydata/xarray/issues/2007,375681041,MDEyOklzc3VlQ29tbWVudDM3NTY4MTA0MQ==,6815844,2018-03-23T14:22:57Z,2018-03-23T14:22:57Z,MEMBER,"@maxim-lian , do you agree to add this feature?
Although the same behavior can be realized by adding head/tail values to the original array and truncate them after the computation, the `periodic` option would significantly simplify this.","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,307783090
https://github.com/pydata/xarray/issues/2007#issuecomment-375476906,https://api.github.com/repos/pydata/xarray/issues/2007,375476906,MDEyOklzc3VlQ29tbWVudDM3NTQ3NjkwNg==,6815844,2018-03-22T22:22:26Z,2018-03-22T22:22:26Z,MEMBER,"I think the implementation would be not so difficult by supporting more flexible `fill_value` option in [`xr.DataArrayRolling.construct` method](http://xarray.pydata.org/en/stable/generated/xarray.core.rolling.DataArrayRolling.construct.html#xarray.core.rolling.DataArrayRolling.construct).

Maybe `fill_value='periodic'` would be a possible API,
```python
da.rolling(dayofyear=31).construct('window', fill_value='periodic').mean('window')
```

@mathause, any interest in contributing?","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,307783090