resubMargin

Class: ClassificationDiscriminant

Classification margins by resubstitution

Syntax

M = resubMargin(obj)

Description

M = resubMargin(obj) returns resubstitution classification margins for obj.

Input Arguments

obj

Discriminant analysis classifier, produced using fitcdiscr.

Output Arguments

M

Numeric column-vector of length size(obj.X,1) containing the classification margins.

Definitions

Margin

The classification margin is the difference between the classification score for the true class and maximal classification score for the false classes.

The classification margin is a column vector with the same number of rows as in the matrix X. A high value of margin indicates a more reliable prediction than a low value.

Score

For discriminant analysis, the score of a classification is the posterior probability of the classification. For the definition of posterior probability in discriminant analysis, see Posterior Probability.

Examples

expand all

Estimate Resubstitution Margins for Discriminant Analysis Classifiers

Find the margins for a discriminant analysis classifier for Fisher's iris data by resubstitution. Examine several entries.

Load Fisher's iris data set.

load fisheriris

Train a discriminant analysis classifier.

Mdl = fitcdiscr(meas,species);

Compute the resubstitution margins, and display several of them.

m = resubMargin(Mdl);
m(1:25:end)
ans =

    1.0000
    1.0000
    0.9998
    0.9998
    1.0000
    0.9946

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