[MRG] DOC Mention StandardScaler ddof#12950

Merged

qinhanmin2014 merged 7 commits intoscikit-learn:masterfrom

MarcoGorelli:fix-doc-standardscaler

Jan 14, 2019

Commits on Jan 10, 2019

Update docstring of preprocessing.StandardScaler so it's clear that the estimator of the standard deviation is the biased one
Marco Gorelli
committed
Add np.sqrt to calculation of standard deviation
Marco Gorelli
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Change np to numpy
Marco Gorelli
committed

Commits on Jan 11, 2019

Add message explaning it's unlikely that the choice of estimator would affect model performance.
Marco Gorelli
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Move note about ddof in StandardScaler to 'Notes' section, and use np.std instead of np.var
Marco Gorelli
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Remove 'however'
Marco Gorelli
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Commits on Jan 14, 2019

Replicate note in the function
Marco Gorelli
committed