package sklearn

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Scikit-learn machine learning library for OCaml

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Authors

  1. R
    Ronan Le Hy

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  1. R
    Ronan Le Hy <ronan.lehy@gmail.com>

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sklearn-v0.3.1.tbz
sha256=48809d88893a3f17d79f8e5acbd28126de919b8ced6d1f6856a61fd6bfae571d
sha512=9e1d01c42aed436163b1ce50bee141f40cb5bc943d5dd16d6eb21f1b53d613933533c70f28675e418a550cf44e0cd66d47496e462132769b05dec64bf3db560c

doc/sklearn/Sklearn/Covariance/OAS/index.html

Module Covariance.OASSource

Sourcetype tag = [
  1. | `OAS
]
Sourcetype t = [ `BaseEstimator | `OAS | `Object ] Obj.t
Sourceval of_pyobject : Py.Object.t -> t
Sourceval to_pyobject : [> tag ] Obj.t -> Py.Object.t
Sourceval as_estimator : t -> [ `BaseEstimator ] Obj.t
Sourceval create : ?store_precision:bool -> ?assume_centered:bool -> unit -> t

Oracle Approximating Shrinkage Estimator

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

OAS is a particular form of shrinkage described in 'Shrinkage Algorithms for MMSE Covariance Estimation' Chen et al., IEEE Trans. on Sign. Proc., Volume 58, Issue 10, October 2010.

The formula used here does not correspond to the one given in the article. In the original article, formula (23) states that 2/p is multiplied by Trace(cov*cov) in both the numerator and denominator, but this operation is omitted because for a large p, the value of 2/p is so small that it doesn't affect the value of the estimator.

Parameters ---------- store_precision : bool, default=True Specify if the estimated precision is stored.

assume_centered : bool, default=False If True, data will not be centered before computation. Useful when working with data whose mean is almost, but not exactly zero. If False (default), data will be centered before computation.

Attributes ---------- covariance_ : ndarray of shape (n_features, n_features) Estimated covariance matrix.

location_ : ndarray of shape (n_features,) Estimated location, i.e. the estimated mean.

precision_ : ndarray of shape (n_features, n_features) Estimated pseudo inverse matrix. (stored only if store_precision is True)

shrinkage_ : float coefficient in the convex combination used for the computation of the shrunk estimate. Range is 0, 1.

Examples -------- >>> import numpy as np >>> from sklearn.covariance import OAS >>> from sklearn.datasets import make_gaussian_quantiles >>> real_cov = np.array([.8, .3], ... [.3, .4]) >>> rng = np.random.RandomState(0) >>> X = rng.multivariate_normal(mean=0, 0, ... cov=real_cov, ... size=500) >>> oas = OAS().fit(X) >>> oas.covariance_ array([0.7533..., 0.2763...], [0.2763..., 0.3964...]) >>> oas.precision_ array([ 1.7833..., -1.2431... ], [-1.2431..., 3.3889...]) >>> oas.shrinkage_ 0.0195...

Notes ----- The regularised covariance is:

(1 - shrinkage) * cov + shrinkage * mu * np.identity(n_features)

where mu = trace(cov) / n_features and shrinkage is given by the OAS formula (see References)

References ---------- 'Shrinkage Algorithms for MMSE Covariance Estimation' Chen et al., IEEE Trans. on Sign. Proc., Volume 58, Issue 10, October 2010.

Sourceval error_norm : ?norm:[ `Frobenius | `Spectral ] -> ?scaling:bool -> ?squared:bool -> comp_cov:[> `ArrayLike ] Np.Obj.t -> [> tag ] Obj.t -> float

Computes the Mean Squared Error between two covariance estimators. (In the sense of the Frobenius norm).

Parameters ---------- comp_cov : array-like of shape (n_features, n_features) The covariance to compare with.

norm : 'frobenius', 'spectral', default='frobenius' The type of norm used to compute the error. Available error types:

  • 'frobenius' (default): sqrt(tr(A^t.A))
  • 'spectral': sqrt(max(eigenvalues(A^t.A)) where A is the error ``(comp_cov - self.covariance_)``.

scaling : bool, default=True If True (default), the squared error norm is divided by n_features. If False, the squared error norm is not rescaled.

squared : bool, default=True Whether to compute the squared error norm or the error norm. If True (default), the squared error norm is returned. If False, the error norm is returned.

Returns ------- result : float The Mean Squared Error (in the sense of the Frobenius norm) between `self` and `comp_cov` covariance estimators.

Sourceval fit : ?y:Py.Object.t -> x:[> `ArrayLike ] Np.Obj.t -> [> tag ] Obj.t -> t

Fit the Oracle Approximating Shrinkage covariance model according to the given training data and parameters.

Parameters ---------- X : array-like of shape (n_samples, n_features) Training data, where `n_samples` is the number of samples and `n_features` is the number of features. y : Ignored not used, present for API consistence purpose.

Returns ------- self : object

Sourceval get_params : ?deep:bool -> [> tag ] Obj.t -> Dict.t

Get parameters for this estimator.

Parameters ---------- deep : bool, default=True If True, will return the parameters for this estimator and contained subobjects that are estimators.

Returns ------- params : mapping of string to any Parameter names mapped to their values.

Sourceval get_precision : [> tag ] Obj.t -> [> `ArrayLike ] Np.Obj.t

Getter for the precision matrix.

Returns ------- precision_ : array-like of shape (n_features, n_features) The precision matrix associated to the current covariance object.

Sourceval mahalanobis : x:[> `ArrayLike ] Np.Obj.t -> [> tag ] Obj.t -> [> `ArrayLike ] Np.Obj.t

Computes the squared Mahalanobis distances of given observations.

Parameters ---------- X : array-like of shape (n_samples, n_features) The observations, the Mahalanobis distances of the which we compute. Observations are assumed to be drawn from the same distribution than the data used in fit.

Returns ------- dist : ndarray of shape (n_samples,) Squared Mahalanobis distances of the observations.

Sourceval score : ?y:Py.Object.t -> x_test:[> `ArrayLike ] Np.Obj.t -> [> tag ] Obj.t -> float

Computes the log-likelihood of a Gaussian data set with `self.covariance_` as an estimator of its covariance matrix.

Parameters ---------- X_test : array-like of shape (n_samples, n_features) Test data of which we compute the likelihood, where n_samples is the number of samples and n_features is the number of features. X_test is assumed to be drawn from the same distribution than the data used in fit (including centering).

y : Ignored Not used, present for API consistence purpose.

Returns ------- res : float The likelihood of the data set with `self.covariance_` as an estimator of its covariance matrix.

Sourceval set_params : ?params:(string * Py.Object.t) list -> [> tag ] Obj.t -> t

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 ---------- **params : dict Estimator parameters.

Returns ------- self : object Estimator instance.

Sourceval covariance_ : t -> [> `ArrayLike ] Np.Obj.t

Attribute covariance_: get value or raise Not_found if None.

Sourceval covariance_opt : t -> [> `ArrayLike ] Np.Obj.t option

Attribute covariance_: get value as an option.

Sourceval location_ : t -> [> `ArrayLike ] Np.Obj.t

Attribute location_: get value or raise Not_found if None.

Sourceval location_opt : t -> [> `ArrayLike ] Np.Obj.t option

Attribute location_: get value as an option.

Sourceval precision_ : t -> [> `ArrayLike ] Np.Obj.t

Attribute precision_: get value or raise Not_found if None.

Sourceval precision_opt : t -> [> `ArrayLike ] Np.Obj.t option

Attribute precision_: get value as an option.

Sourceval shrinkage_ : t -> float

Attribute shrinkage_: get value or raise Not_found if None.

Sourceval shrinkage_opt : t -> float option

Attribute shrinkage_: get value as an option.

Sourceval to_string : t -> string

Print the object to a human-readable representation.

Sourceval show : t -> string

Print the object to a human-readable representation.

Sourceval pp : Format.formatter -> t -> unit

Pretty-print the object to a formatter.