id,node_id,number,state,locked,title,user,body,created_at,updated_at,closed_at,merged_at,merge_commit_sha,assignee,milestone,draft,head,base,author_association,auto_merge,repo,url,merged_by 50911334,MDExOlB1bGxSZXF1ZXN0NTA5MTEzMzQ=,661,closed,0,Document pandas' better groupby performance.,1322974,"cf. #659. ",2015-11-17T07:04:50Z,2015-11-17T09:10:04Z,2015-11-17T08:54:31Z,2015-11-17T08:54:31Z,65099c055dd1636897fdad6c2edae434a0e4aabd,,,0,bad8a7dea7e8b9196c2bab6d22161ed01935d3bd,4f430cd390b3b46cf3d2e66c8c15d01ddea633cc,CONTRIBUTOR,,13221727,https://github.com/pydata/xarray/pull/661,