Standard Scaler

Standardize features by removing the mean and scaling to unit variance.

Centering and scaling happen independently on each feature by computing the relevant statistics on the samples in the training set. Mean and standard deviation are then stored to be used on later data using the transform method. Standardization of a dataset is a common requirement for many machine learning estimators: they might behave badly if the individual feature do not more or less look like standard normally distributed data (e.g. Gaussian with 0 mean and unit variance).

Documentation

Attributes

mean_

The mean value for each feature in the training set. Equal to None when with_mean=False and with_std=False.

n_samples_seen_

The number of samples processed by the estimator for each feature. If there are no missing samples, the n_samples_seen will be an integer, otherwise it will be an array of dtype int. If sample_weights are used it will be a float (if no missing data) or an array of dtype float that sums the weights seen so far. Will be reset on new calls to fit, but increments across partial_fit calls.

scale_

Per feature relative scaling of the data to achieve zero mean and unit variance. Generally this is calculated using np.sqrt(var_). If a variance is zero, we can’t achieve unit variance, and the data is left as-is, giving a scaling factor of 1. scale_ is equal to None when with_std=False.

New in version 0.17: scale_

var_

The variance for each feature in the training set. Used to compute scale_. Equal to None when with_mean=False and with_std=False.

Definition

Output ports

model model

Model

Configuration

Center the data before scaling (with_mean)

If True, center the data before scaling. This does not work (and will raise an exception) when attempted on sparse matrices, because centering them entails building a dense matrix which in common use cases is likely to be too large to fit in memory.

Scale to unit variance (with_std)

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

Implementation

class node_preprocessing.StandardScaler