Linear Discriminant Analysis
A classifier with a linear decision boundary, generated by fitting class conditional densities to the data and using Bayes' rule.
The model fits a Gaussian density to each class, assuming that all classes share the same covariance matrix.
The fitted model can also be used to reduce the dimensionality of the input by projecting it to the most discriminative directions, using the `transform` method.
.. versionadded:: 0.17 *LinearDiscriminantAnalysis*.
Read more in the :ref:`User Guide <lda_qda>`.
Parameters ---------- solver : 'svd', 'lsqr', 'eigen'
, default='svd' Solver to use, possible values:
- 'svd': Singular value decomposition (default). Does not compute the covariance matrix, therefore this solver is recommended for data with a large number of features.
- 'lsqr': Least squares solution, can be combined with shrinkage.
- 'eigen': Eigenvalue decomposition, can be combined with shrinkage.
shrinkage : 'auto' or float, default=None Shrinkage parameter, possible values:
- None: no shrinkage (default).
- 'auto': automatic shrinkage using the Ledoit-Wolf lemma.
- float between 0 and 1: fixed shrinkage parameter.
Note that shrinkage works only with 'lsqr' and 'eigen' solvers.
priors : array-like of shape (n_classes,), default=None The class prior probabilities. By default, the class proportions are inferred from the training data.
n_components : int, default=None Number of components (<= min(n_classes - 1, n_features)) for dimensionality reduction. If None, will be set to min(n_classes - 1, n_features). This parameter only affects the `transform` method.
store_covariance : bool, default=False If True, explicitely compute the weighted within-class covariance matrix when solver is 'svd'. The matrix is always computed and stored for the other solvers.
.. versionadded:: 0.17
tol : float, default=1.0e-4 Absolute threshold for a singular value of X to be considered significant, used to estimate the rank of X. Dimensions whose singular values are non-significant are discarded. Only used if solver is 'svd'.
.. versionadded:: 0.17
Attributes ---------- coef_ : ndarray of shape (n_features,) or (n_classes, n_features) Weight vector(s).
intercept_ : ndarray of shape (n_classes,) Intercept term.
covariance_ : array-like of shape (n_features, n_features) Weighted within-class covariance matrix. It corresponds to `sum_k prior_k * C_k` where `C_k` is the covariance matrix of the samples in class `k`. The `C_k` are estimated using the (potentially shrunk) biased estimator of covariance. If solver is 'svd', only exists when `store_covariance` is True.
explained_variance_ratio_ : ndarray of shape (n_components,) Percentage of variance explained by each of the selected components. If ``n_components`` is not set then all components are stored and the sum of explained variances is equal to 1.0. Only available when eigen or svd solver is used.
means_ : array-like of shape (n_classes, n_features) Class-wise means.
priors_ : array-like of shape (n_classes,) Class priors (sum to 1).
scalings_ : array-like of shape (rank, n_classes - 1) Scaling of the features in the space spanned by the class centroids. Only available for 'svd' and 'eigen' solvers.
xbar_ : array-like of shape (n_features,) Overall mean. Only present if solver is 'svd'.
classes_ : array-like of shape (n_classes,) Unique class labels.
See also -------- sklearn.discriminant_analysis.QuadraticDiscriminantAnalysis: Quadratic Discriminant Analysis
Examples -------- >>> import numpy as np >>> from sklearn.discriminant_analysis import LinearDiscriminantAnalysis >>> X = np.array([-1, -1], [-2, -1], [-3, -2], [1, 1], [2, 1], [3, 2]
) >>> y = np.array(1, 1, 1, 2, 2, 2
) >>> clf = LinearDiscriminantAnalysis() >>> clf.fit(X, y) LinearDiscriminantAnalysis() >>> print(clf.predict([-0.8, -1]
)) 1