package sklearn

Get an attribute of this module as a Py.Object.t. This is useful to pass a Python function to another function.

Augment dataset with an additional dummy feature.

This is useful for fitting an intercept term with implementations which cannot otherwise fit it directly.

Parameters ---------- X : array-like, sparse matrix, shape n_samples, n_features Data.

value : float Value to use for the dummy feature.

Returns -------

X : array, sparse matrix, shape n_samples, n_features + 1 Same data with dummy feature added as first column.

Examples --------

>>> from sklearn.preprocessing import add_dummy_feature >>> add_dummy_feature([0, 1], [1, 0]) array([1., 0., 1.], [1., 1., 0.])

Boolean thresholding of array-like or scipy.sparse matrix

Read more in the :ref:`User Guide <preprocessing_binarization>`.

Parameters ---------- X : array-like, sparse matrix, shape n_samples, n_features The data to binarize, element by element. scipy.sparse matrices should be in CSR or CSC format to avoid an un-necessary copy.

threshold : float, optional (0.0 by default) Feature values below or equal to this are replaced by 0, above it by 1. Threshold may not be less than 0 for operations on sparse matrices.

copy : boolean, optional, default True set to False to perform inplace binarization and avoid a copy (if the input is already a numpy array or a scipy.sparse CSR / CSC matrix and if axis is 1).

See also -------- Binarizer: Performs binarization using the ``Transformer`` API (e.g. as part of a preprocessing :class:`sklearn.pipeline.Pipeline`).

Binarize labels in a one-vs-all fashion

Several regression and binary classification algorithms are available in scikit-learn. A simple way to extend these algorithms to the multi-class classification case is to use the so-called one-vs-all scheme.

This function makes it possible to compute this transformation for a fixed set of class labels known ahead of time.

Parameters ---------- y : array-like Sequence of integer labels or multilabel data to encode.

classes : array-like of shape n_classes Uniquely holds the label for each class.

neg_label : int (default: 0) Value with which negative labels must be encoded.

pos_label : int (default: 1) Value with which positive labels must be encoded.

sparse_output : boolean (default: False), Set to true if output binary array is desired in CSR sparse format

Returns ------- Y : numpy array or CSR matrix of shape n_samples, n_classes Shape will be n_samples, 1 for binary problems.

Examples -------- >>> from sklearn.preprocessing import label_binarize >>> label_binarize(1, 6, classes=1, 2, 4, 6) array([1, 0, 0, 0], [0, 0, 0, 1])

The class ordering is preserved:

>>> label_binarize(1, 6, classes=1, 6, 4, 2) array([1, 0, 0, 0], [0, 1, 0, 0])

Binary targets transform to a column vector

>>> label_binarize('yes', 'no', 'no', 'yes', classes='no', 'yes') array([1], [0], [0], [1])

See also -------- LabelBinarizer : class used to wrap the functionality of label_binarize and allow for fitting to classes independently of the transform operation

Scale each feature to the -1, 1 range without breaking the sparsity.

This estimator scales each feature individually such that the maximal absolute value of each feature in the training set will be 1.0.

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

Parameters ---------- X : array-like, shape (n_samples, n_features) The data.

axis : int (0 by default) axis used to scale along. If 0, independently scale each feature, otherwise (if 1) scale each sample.

copy : boolean, optional, default is True Set to False to perform inplace scaling and avoid a copy (if the input is already a numpy array).

See also -------- MaxAbsScaler: Performs scaling to the -1, 1 range using the``Transformer`` API (e.g. as part of a preprocessing :class:`sklearn.pipeline.Pipeline`).

Notes ----- NaNs are treated as missing values: disregarded to compute the statistics, and maintained during the data transformation.

For a comparison of the different scalers, transformers, and normalizers, see :ref:`examples/preprocessing/plot_all_scaling.py <sphx_glr_auto_examples_preprocessing_plot_all_scaling.py>`.

Transform features by scaling each feature to a given range.

This estimator scales and translates each feature individually such that it is in the given range on the training set, i.e. between zero and one.

The transformation is given by (when ``axis=0``)::

X_std = (X - X.min(axis=0)) / (X.max(axis=0) - X.min(axis=0)) X_scaled = X_std * (max - min) + min

where min, max = feature_range.

The transformation is calculated as (when ``axis=0``)::

X_scaled = scale * X + min - X.min(axis=0) * scale where scale = (max - min) / (X.max(axis=0) - X.min(axis=0))

This transformation is often used as an alternative to zero mean, unit variance scaling.

Read more in the :ref:`User Guide <preprocessing_scaler>`.

.. versionadded:: 0.17 *minmax_scale* function interface to :class:`sklearn.preprocessing.MinMaxScaler`.

Parameters ---------- X : array-like of shape (n_samples, n_features) The data.

feature_range : tuple (min, max), default=(0, 1) Desired range of transformed data.

axis : int, default=0 Axis used to scale along. If 0, independently scale each feature, otherwise (if 1) scale each sample.

copy : bool, default=True Set to False to perform inplace scaling and avoid a copy (if the input is already a numpy array).

See also -------- MinMaxScaler: Performs scaling to a given range using the``Transformer`` API (e.g. as part of a preprocessing :class:`sklearn.pipeline.Pipeline`).

Notes ----- For a comparison of the different scalers, transformers, and normalizers, see :ref:`examples/preprocessing/plot_all_scaling.py <sphx_glr_auto_examples_preprocessing_plot_all_scaling.py>`.

Scale input vectors individually to unit norm (vector length).

Read more in the :ref:`User Guide <preprocessing_normalization>`.

Parameters ---------- X : array-like, sparse matrix, shape n_samples, n_features The data to normalize, element by element. scipy.sparse matrices should be in CSR format to avoid an un-necessary copy.

norm : 'l1', 'l2', or 'max', optional ('l2' by default) The norm to use to normalize each non zero sample (or each non-zero feature if axis is 0).

axis : 0 or 1, optional (1 by default) axis used to normalize the data along. If 1, independently normalize each sample, otherwise (if 0) normalize each feature.

copy : boolean, optional, default 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).

return_norm : boolean, default False whether to return the computed norms

Returns ------- X : array-like, sparse matrix, shape n_samples, n_features Normalized input X.

norms : array, shape n_samples if axis=1 else n_features An array of norms along given axis for X. When X is sparse, a NotImplementedError will be raised for norm 'l1' or 'l2'.

See also -------- Normalizer: Performs normalization using the ``Transformer`` API (e.g. as part of a preprocessing :class:`sklearn.pipeline.Pipeline`).

Notes ----- For a comparison of the different scalers, transformers, and normalizers, see :ref:`examples/preprocessing/plot_all_scaling.py <sphx_glr_auto_examples_preprocessing_plot_all_scaling.py>`.

Power transforms are a family of parametric, monotonic transformations that are applied to make data more Gaussian-like. This is useful for modeling issues related to heteroscedasticity (non-constant variance), or other situations where normality is desired.

Currently, power_transform supports the Box-Cox transform and the Yeo-Johnson transform. The optimal parameter for stabilizing variance and minimizing skewness is estimated through maximum likelihood.

Box-Cox requires input data to be strictly positive, while Yeo-Johnson supports both positive or negative data.

By default, zero-mean, unit-variance normalization is applied to the transformed data.

Read more in the :ref:`User Guide <preprocessing_transformer>`.

Parameters ---------- X : array-like, shape (n_samples, n_features) The data to be transformed using a power transformation.

method : 'yeo-johnson', 'box-cox', default='yeo-johnson' The power transform method. Available methods are:

• 'yeo-johnson' 1_, works with positive and negative values
• 'box-cox' 2_, only works with strictly positive values

.. versionchanged:: 0.23 The default value of the `method` parameter changed from 'box-cox' to 'yeo-johnson' in 0.23.

standardize : boolean, default=True Set to True to apply zero-mean, unit-variance normalization to the transformed output.

copy : boolean, optional, default=True Set to False to perform inplace computation during transformation.

Returns ------- X_trans : array-like, shape (n_samples, n_features) The transformed data.

Examples -------- >>> import numpy as np >>> from sklearn.preprocessing import power_transform >>> data = [1, 2], [3, 2], [4, 5] >>> print(power_transform(data, method='box-cox')) [-1.332... -0.707...] [ 0.256... -0.707...] [ 1.076... 1.414...]

See also -------- PowerTransformer : Equivalent transformation with the ``Transformer`` API (e.g. as part of a preprocessing :class:`sklearn.pipeline.Pipeline`).

quantile_transform : Maps data to a standard normal distribution with the parameter `output_distribution='normal'`.

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 :ref:`examples/preprocessing/plot_all_scaling.py <sphx_glr_auto_examples_preprocessing_plot_all_scaling.py>`.

References ----------

.. 1 I.K. Yeo and R.A. Johnson, 'A new family of power transformations to improve normality or symmetry.' Biometrika, 87(4), pp.954-959, (2000).

.. 2 G.E.P. Box and D.R. Cox, 'An Analysis of Transformations', Journal of the Royal Statistical Society B, 26, 211-252 (1964).

Transform features using quantiles information.

This method transforms the features to follow a uniform or a normal distribution. Therefore, for a given feature, this transformation tends to spread out the most frequent values. It also reduces the impact of (marginal) outliers: this is therefore a robust preprocessing scheme.

The transformation is applied on each feature independently. First an estimate of the cumulative distribution function of a feature is used to map the original values to a uniform distribution. The obtained values are then mapped to the desired output distribution using the associated quantile function. Features values of new/unseen data that fall below or above the fitted range will be mapped to the bounds of the output distribution. Note that this transform is non-linear. It may distort linear correlations between variables measured at the same scale but renders variables measured at different scales more directly comparable.

Read more in the :ref:`User Guide <preprocessing_transformer>`.

Parameters ---------- X : array-like, sparse matrix The data to transform.

axis : int, (default=0) Axis used to compute the means and standard deviations along. If 0, transform each feature, otherwise (if 1) transform each sample.

n_quantiles : int, optional (default=1000 or n_samples) Number of quantiles to be computed. It corresponds to the number of landmarks used to discretize the cumulative distribution function. If n_quantiles is larger than the number of samples, n_quantiles is set to the number of samples as a larger number of quantiles does not give a better approximation of the cumulative distribution function estimator.

output_distribution : str, optional (default='uniform') Marginal distribution for the transformed data. The choices are 'uniform' (default) or 'normal'.

ignore_implicit_zeros : bool, optional (default=False) Only applies to sparse matrices. If True, the sparse entries of the matrix are discarded to compute the quantile statistics. If False, these entries are treated as zeros.

subsample : int, optional (default=1e5) Maximum number of samples used to estimate the quantiles for computational efficiency. Note that the subsampling procedure may differ for value-identical sparse and dense matrices.

random_state : int, RandomState instance or None, optional (default=None) Determines random number generation for subsampling and smoothing noise. Please see ``subsample`` for more details. Pass an int for reproducible results across multiple function calls. See :term:`Glossary <random_state>`

copy : boolean, optional, (default=True) Set to False to perform inplace transformation and avoid a copy (if the input is already a numpy array). If True, a copy of `X` is transformed, leaving the original `X` unchanged

..versionchanged:: 0.23 The default value of `copy` changed from False to True in 0.23.

Returns ------- Xt : ndarray or sparse matrix, shape (n_samples, n_features) The transformed data.

Examples -------- >>> import numpy as np >>> from sklearn.preprocessing import quantile_transform >>> rng = np.random.RandomState(0) >>> X = np.sort(rng.normal(loc=0.5, scale=0.25, size=(25, 1)), axis=0) >>> quantile_transform(X, n_quantiles=10, random_state=0, copy=True) array(...)

See also -------- QuantileTransformer : Performs quantile-based scaling using the ``Transformer`` API (e.g. as part of a preprocessing :class:`sklearn.pipeline.Pipeline`). power_transform : Maps data to a normal distribution using a power transformation. scale : Performs standardization that is faster, but less robust to outliers. robust_scale : Performs robust standardization that removes the influence of outliers but does not put outliers and inliers on the same scale.

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 :ref:`examples/preprocessing/plot_all_scaling.py <sphx_glr_auto_examples_preprocessing_plot_all_scaling.py>`.

Standardize a dataset along any axis

Center to the median and component wise scale according to the interquartile range.

Read more in the :ref:`User Guide <preprocessing_scaler>`.

Parameters ---------- X : array-like The data to center and scale.

axis : int (0 by default) axis used to compute the medians and IQR along. If 0, independently scale each feature, otherwise (if 1) scale each sample.

with_centering : boolean, True by default If True, center the data before scaling.

with_scaling : boolean, True by default If True, scale the data to unit variance (or equivalently, unit standard deviation).

quantile_range : tuple (q_min, q_max), 0.0 < q_min < q_max < 100.0 Default: (25.0, 75.0) = (1st quantile, 3rd quantile) = IQR Quantile range used to calculate ``scale_``.

.. versionadded:: 0.18

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).

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_centering=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.

For a comparison of the different scalers, transformers, and normalizers, see :ref:`examples/preprocessing/plot_all_scaling.py <sphx_glr_auto_examples_preprocessing_plot_all_scaling.py>`.

See also -------- RobustScaler: Performs centering and scaling using the ``Transformer`` API (e.g. as part of a preprocessing :class:`sklearn.pipeline.Pipeline`).

Standardize a dataset along any axis

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

Read more in the :ref:`User Guide <preprocessing_scaler>`.

Parameters ---------- X : array-like, sparse 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 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 CSC matrix and if axis is 1).

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 CSC 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 CSC matrix.

NaNs are treated as missing values: disregarded to compute the statistics, and maintained during the data transformation.

We use a biased estimator for the standard deviation, equivalent to `numpy.std(x, ddof=0)`. Note that the choice of `ddof` is unlikely to affect model performance.

For a comparison of the different scalers, transformers, and normalizers, see :ref:`examples/preprocessing/plot_all_scaling.py <sphx_glr_auto_examples_preprocessing_plot_all_scaling.py>`.

See also -------- StandardScaler: Performs scaling to unit variance using the``Transformer`` API (e.g. as part of a preprocessing :class:`sklearn.pipeline.Pipeline`).