[BUG-REPORT] Sometimes std returns nan when it shouldn't

[Ben-Epstein]

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Description

import vaex

vaex.from_arrays(value=[0.0179862099620915]*100).value.std()  # nan
vaex.from_arrays(value=[0.0179862099620915]*100).to_pandas_df().value.std()  # ~0

Software information

• Vaex version (import vaex; vaex.__version__): 4.12.0
• Vaex was installed via: pip / conda-forge / from source
• OS:

Additional information
Please state any supplementary information or provide additional context for the problem (e.g. screenshots, data, etc..).

[JovanVeljanoski]

Hi Ben!

Thanks for this. I just pushed a quick fix. Hopefully @maartenbreddels manages to have a look at it soon.

Note: even with the fix there will be some difference for this case compared to pandas/numpy. This is because vaex uses an unstable algorithm for this. But I think that is relevant mainly for this edge case, where the variance is sooo small (close to 0).