# Standardizes features by removing the mean and scaling to unit variance

Source:`R/sklearn-scalers.R`

`StandardScaler.Rd`

The standard score of a sample x is calculated as:
$$z = \frac{(x - u)}{s}$$
where \(u\) is the mean of the training samples or 0 if `with_mean = FALSE`

, and \(s\) is the standard deviation of the training samples or 1 if
`with_std = FALSE`

.

Standardization of a dataset is a common requirement for many machine learning estimators: they might behave badly if the individual features do not more or less look like standard normally distributed data (e.g. Gaussian with 0 mean and unit variance).

For instance many elements used in the objective function of a learning algorithm (such as the RBF kernel of Support Vector Machines or the L1 and L2 regularizers of linear models) assume that all features are centered around 0 and have variance in the same order. If a feature has a variance that is orders of magnitude larger than others, it might dominate the objective function and make the estimator unable to learn from other features correctly as expected.

This scaler can also be applied to sparse CSR or CSC matrices by passing
`with_mean = FALSE`

to avoid breaking the sparsity structure of the data.

## Super classes

`rgudhi::PythonClass`

-> `rgudhi::SKLearnClass`

-> `rgudhi::BaseScaler`

-> `StandardScaler`

## Methods

## Inherited methods

### Method `new()`

The StandardScaler class constructor.

#### Usage

`StandardScaler$new(copy = TRUE, with_mean = TRUE, with_std = TRUE)`

#### Arguments

`copy`

A boolean value specifying whether to perform in-place scaling and avoid a copy (if the input is already a numpy array). Defaults to

`TRUE`

.`with_mean`

A boolean value specifying whether to 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. Defaults to

`TRUE`

.`with_std`

A boolean value specifying whether to scale the data to unit variance (or equivalently, unit standard deviation). Defaults to

`TRUE`

.