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/5877#issuecomment-947906426,https://api.github.com/repos/pydata/xarray/issues/5877,947906426,IC_kwDOAMm_X844f-d6,8453445,2021-10-20T17:59:13Z,2021-10-20T17:59:13Z,CONTRIBUTOR,"Yup - just followed your suggestion and:

1) conda removed `bottleneck` and it removed xarray and pandas as well
2) conda installed `xarray` which installed `xarray`, `pandas`, and `pytz`

and now the `xr.rolling(time=3).sum()` yields:

array([        nan,         nan,  0.        ,  0.        ,  0.        ,
        0.        ,  0.        ,  0.31      ,  1.23      ,  9.530001  ,
       10.64      ,  9.75      ,  2.67      ,  1.35      ,  1.46      ,
        0.36999997,  0.26999998,  0.25      ,  0.14999999,  2.68      ,
        2.56      ,  2.73      ,  0.39999998,  0.39999998,  0.19999999,
        0.        ,  0.        ,  0.        ,  0.        ,  0.        ,
        0.        ,  0.        ,  0.        ,  0.        ,  0.        ],
      dtype=float32)

could you elaborate more on the issue? is this because of some bouncing between precisions across packages?
But why do I have zeros at the beginning of the rolling sum and non zeros after having calculated a sum? 
it is not consistent in the behaviour. 

Thanks tho! 



","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,1030768250
https://github.com/pydata/xarray/issues/5877#issuecomment-947195221,https://api.github.com/repos/pydata/xarray/issues/5877,947195221,IC_kwDOAMm_X844dQ1V,8453445,2021-10-20T00:02:58Z,2021-10-20T00:02:58Z,CONTRIBUTOR,"Adding a few extra observations:

```python
ds_ex.rolling(time=3).mean().pr.values
df_ex.rolling(window=3).mean().values.T
```
have a similar behaviour, in that once again `xr.rolling()` doesn't have zero where it should, but `pd.rolling` does.

But when I switch to other operations, like `var` or `std` the behaviour is the opposite, i.e.:
```
ds_ex.rolling(time=3).std().pr.values
```
array([       nan,        nan, 0.        , 0.        , 0.        ,
       0.        , 0.        , 0.1461354 , 0.38218665, 3.631293  ,
       3.367307  , 3.6156974 , 0.61356837, 0.54522127, 0.5188016 ,
       0.01698606, 0.06376763, 0.05906381, 0.05098677, 1.157881  ,
       1.1856455 , 1.148419  , 0.09427918, 0.09427918, 0.09427926,
       0.        , 0.        , 0.        , 0.        , 0.        ,
       0.        , 0.        , 0.        , 0.        , 0.        ],
      dtype=float32)

whereas

```
df_ex.rolling(window=3).std().values.T
```
gives

array([[           nan,            nan, 0.00000000e+00, 0.00000000e+00,
        0.00000000e+00, 0.00000000e+00, 0.00000000e+00, 1.78978585e-01,
        4.68081166e-01, 4.44740760e+00, 4.12409195e+00, 4.42830679e+00,
        7.51465227e-01, 6.67757461e-01, 6.35400157e-01, 2.08166670e-02,
        7.81024957e-02, 7.23417792e-02, 6.24499786e-02, 1.41810905e+00,
        1.45211339e+00, 1.40652052e+00, 1.15470047e-01, 1.15470047e-01,
        1.15470047e-01, 9.60572442e-08, 9.60572442e-08, 9.60572442e-08,
        9.60572442e-08, 9.60572442e-08, 9.60572442e-08, 9.60572442e-08,
        9.60572442e-08, 9.60572442e-08, 9.60572442e-08]])","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,1030768250