edge

Classification edge

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Syntax

E = edge(ens,tbl,ResponseVarName)
E = edge(ens,tbl,Y)
E = edge(ens,X,Y)
E = edge(___,Name,Value)

Description

E = edge(ens,tbl,ResponseVarName) returns the classification edge for ens with data tbl and classification tbl.ResponseVarName.

E = edge(ens,tbl,Y) returns the classification edge for ens with data tbl and classification Y.

E = edge(ens,X,Y) returns the classification edge for ens with data X and classification Y.

E = edge(___,Name,Value) computes the edge with additional options specified by one or more Name,Value pair arguments, using any of the previous syntaxes.

Input Arguments

ens

A classification ensemble constructed with fitcensemble, or a compact classification ensemble constructed with compact.

tbl

Sample data, specified as a table. Each row of tbl corresponds to one observation, and each column corresponds to one predictor variable. tbl must contain all of the predictors used to train the model. Multi-column variables and cell arrays other than cell arrays of character vectors are not allowed.

If you trained ens using sample data contained in a table, then the input data for this method must also be in a table.

ResponseVarName

Response variable name, specified as the name of a variable in tbl.

You must specify ResponseVarName as a character vector or string scalar. For example, if the response variable Y is stored as tbl.Y, then specify it as 'Y'. Otherwise, the software treats all columns of tbl, including Y, as predictors when training the model.

X

A matrix where each row represents an observation, and each column represents a predictor. The number of columns in X must equal the number of predictors in ens.

If you trained ens using sample data contained in a matrix, then the input data for this method must also be in a matrix.

Y

Class labels of observations in tbl or X. Y should be of the same type as the classification used to train ens, and its number of elements should equal the number of rows of tbl or X.

Name-Value Pair Arguments

Specify optional comma-separated pairs of Name,Value arguments. Name is the argument name and Value is the corresponding value. Name must appear inside quotes. You can specify several name and value pair arguments in any order as Name1,Value1,...,NameN,ValueN.

'learners'

Indices of weak learners in the ensemble ranging from 1 to ens.NumTrained. edge uses only these learners for calculating loss.

Default: 1:NumTrained

'mode'

Meaning of the output E:

  • 'ensemble' — E is a scalar value, the edge for the entire ensemble.

  • 'individual' — E is a vector with one element per trained learner.

  • 'cumulative' — E is a vector in which element J is obtained by using learners 1:J from the input list of learners.

Default: 'ensemble'

'UseObsForLearner'

A logical matrix of size N-by-T, where:

  • N is the number of rows of X.

  • T is the number of weak learners in ens.

When UseObsForLearner(i,j) is true, learner j is used in predicting the class of row i of X.

Default: true(N,T)

'weights'

Observation weights, a numeric vector of length size(X,1). If you supply weights, edge computes weighted classification edge.

Default: ones(size(X,1),1)

Output Arguments

E

The classification edge, a vector or scalar depending on the setting of the mode name-value pair. Classification edge is weighted average classification margin.

Examples

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Open Live Script

Find the classification edge for some of the data used to train a boosted ensemble classifier.

Load the ionosphere data set.

load ionosphere

Train an ensemble of 100 boosted classification trees using AdaBoostM1.

t = templateTree('MaxNumSplits',1); % Weak learner template tree object
ens = fitcensemble(X,Y,'Method','AdaBoostM1','Learners',t);

Find the classification edge for the last few rows.

E = edge(ens,X(end-10:end,:),Y(end-10:end))
E = 8.3310

More About

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Extended Capabilities

See Also

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Statistics and Machine Learning Toolbox Documentation

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