8.23.6. sklearn.preprocessing.scale

sklearn.preprocessing.scale(X, axis=0, with_mean=True, with_std=True, copy=True)

Standardize a dataset along any axis

Center to the mean and component wise scale to unit variance.

Parameters :

X : array-like or CSR matrix.

The data to center and scale.

axis : int (0 by default)

axis used to compute the means and standard deviations along. If 0, independently standardize each feature, otherwise (if 1) standardize each sample.

with_mean : boolean, True by default

If True, center the data before scaling.

with_std : boolean, True by default

If True, scale the data to unit variance (or equivalently, unit standard deviation).

copy : boolean, optional, default is True

set to False to perform inplace row normalization and avoid a copy (if the input is already a numpy array or a scipy.sparse CSR matrix and if axis is 1).

See also

sklearn.preprocessing.Scaler, scaling, sklearn.pipeline.Pipeline

Notes

This implementation will refuse to center scipy.sparse matrices since it would make them non-sparse and would potentially crash the program with memory exhaustion problems.

Instead the caller is expected to either set explicitly with_mean=False (in that case, only variance scaling will be performed on the features of the CSR matrix) or to call X.toarray() if he/she expects the materialized dense array to fit in memory.

To avoid memory copy the caller should pass a CSR matrix.