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
250751931,MDU6SXNzdWUyNTA3NTE5MzE=,1509,Unexpected behavior with DataArray.resample(how='sum') in presence of NaNs,5564291,closed,0,,,3,2017-08-16T20:36:28Z,2017-08-17T15:20:22Z,2017-08-16T23:23:38Z,NONE,,,,"The behavior of DataArray.resample is different for 'sum' and 'mean':
```
import xarray as xr
import numpy as np
import pandas as pd
x = xr.DataArray([1, np.nan], coords=[('t', pd.date_range('2017-08-01', '2017-08-02'))])
x.resample('D', 't', how='mean')         # returns [1, nan]
x.resample('D', 't', how='sum')           # returns [1, 0]
```
Setting skipna=False returns [1, nan] in both cases. I find the behavior of 'sum' unexpected. ","{""url"": ""https://api.github.com/repos/pydata/xarray/issues/1509/reactions"", ""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,completed,13221727,issue