# sklearn.preprocessing.MaxAbsScaler¶

class sklearn.preprocessing.MaxAbsScaler(*, copy=True)[source]

Scale each feature by its maximum absolute value.

This estimator scales and translates each feature individually such that the maximal absolute value of each feature in the training set will be 1.0. It does not shift/center the data, and thus does not destroy any sparsity.

This scaler can also be applied to sparse CSR or CSC matrices.

New in version 0.17.

Parameters
copybool, default=True

Set to False to perform inplace scaling and avoid a copy (if the input is already a numpy array).

Attributes
scale_ndarray of shape (n_features,)

Per feature relative scaling of the data.

New in version 0.17: scale_ attribute.

max_abs_ndarray of shape (n_features,)

Per feature maximum absolute value.

n_samples_seen_int

The number of samples processed by the estimator. Will be reset on new calls to fit, but increments across partial_fit calls.

See also

maxabs_scale

Equivalent function without the estimator API.

Notes

NaNs are treated as missing values: disregarded in fit, and maintained in transform.

For a comparison of the different scalers, transformers, and normalizers, see examples/preprocessing/plot_all_scaling.py.

Examples

>>> from sklearn.preprocessing import MaxAbsScaler
>>> X = [[ 1., -1.,  2.],
...      [ 2.,  0.,  0.],
...      [ 0.,  1., -1.]]
>>> transformer = MaxAbsScaler().fit(X)
>>> transformer
MaxAbsScaler()
>>> transformer.transform(X)
array([[ 0.5, -1. ,  1. ],
[ 1. ,  0. ,  0. ],
[ 0. ,  1. , -0.5]])


Methods

 fit(X[, y]) Compute the maximum absolute value to be used for later scaling. fit_transform(X[, y]) Fit to data, then transform it. get_params([deep]) Get parameters for this estimator. Scale back the data to the original representation partial_fit(X[, y]) Online computation of max absolute value of X for later scaling. set_params(**params) Set the parameters of this estimator. Scale the data
fit(X, y=None)[source]

Compute the maximum absolute value to be used for later scaling.

Parameters
X{array-like, sparse matrix} of shape (n_samples, n_features)

The data used to compute the per-feature minimum and maximum used for later scaling along the features axis.

yNone

Ignored.

Returns
selfobject

Fitted scaler.

fit_transform(X, y=None, **fit_params)[source]

Fit to data, then transform it.

Fits transformer to X and y with optional parameters fit_params and returns a transformed version of X.

Parameters
X{array-like, sparse matrix, dataframe} of shape (n_samples, n_features)

Input samples.

yndarray of shape (n_samples,), default=None

Target values (None for unsupervised transformations).

**fit_paramsdict

Additional fit parameters.

Returns
X_newndarray array of shape (n_samples, n_features_new)

Transformed array.

get_params(deep=True)[source]

Get parameters for this estimator.

Parameters
deepbool, default=True

If True, will return the parameters for this estimator and contained subobjects that are estimators.

Returns
paramsmapping of string to any

Parameter names mapped to their values.

inverse_transform(X)[source]

Scale back the data to the original representation

Parameters
X{array-like, sparse matrix} of shape (n_samples, n_features)

The data that should be transformed back.

Returns
X_tr{ndarray, sparse matrix} of shape (n_samples, n_features)

Transformed array.

partial_fit(X, y=None)[source]

Online computation of max absolute value of X for later scaling.

All of X is processed as a single batch. This is intended for cases when fit is not feasible due to very large number of n_samples or because X is read from a continuous stream.

Parameters
X{array-like, sparse matrix} of shape (n_samples, n_features)

The data used to compute the mean and standard deviation used for later scaling along the features axis.

yNone

Ignored.

Returns
selfobject

Fitted scaler.

set_params(**params)[source]

Set the parameters of this estimator.

The method works on simple estimators as well as on nested objects (such as pipelines). The latter have parameters of the form <component>__<parameter> so that it’s possible to update each component of a nested object.

Parameters
**paramsdict

Estimator parameters.

Returns
selfobject

Estimator instance.

transform(X)[source]

Scale the data

Parameters
X{array-like, sparse matrix} of shape (n_samples, n_features)

The data that should be scaled.

Returns
X_tr{ndarray, sparse matrix} of shape (n_samples, n_features)

Transformed array.