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-948691519,https://api.github.com/repos/pydata/xarray/issues/5877,948691519,IC_kwDOAMm_X844i-I_,10194086,2021-10-21T14:45:47Z,2021-10-21T14:45:47Z,MEMBER,"AFAIK bottleneck uses a less precise algorithm for sums than numpy (pydata/bottleneck#379). However, I don't know why this yields 0 at the beginning but not at the end. A slightly more minimal example: ```python import bottleneck as bn import numpy as np import pandas as pd data = np.array( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.31, 0.91999996, 8.3, 1.42, 0.03, 1.22, 0.09999999, 0.14, 0.13, 0.0, 0.12, 0.03, 2.53, 0.0, 0.19999999, 0.19999999, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, ], dtype=""float32"", ) bn.move_sum(data, window=3) pd.Series(data).rolling(3).mean() np.convolve(data, np.ones(3), 'valid') / 3 ```","{""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-947893467,https://api.github.com/repos/pydata/xarray/issues/5877,947893467,IC_kwDOAMm_X844f7Tb,10194086,2021-10-20T17:41:04Z,2021-10-20T17:41:04Z,MEMBER,Thanks for the report. Without testing anything I suspect that this is due to the use of `float32` data and/ or bottleneck - see also #1346. You can test this by uninstalling bottleneck (there is an option to disable bottleneck but it's not yet released (#5560).,"{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,1030768250