crossval

Class: ClassificationTree

Cross-validated decision tree

Syntax

cvmodel = crossval(model)
cvmodel = crossval(model,Name,Value)

Description

cvmodel = crossval(model) creates a partitioned model from model, a fitted classification tree. By default, crossval uses 10-fold cross validation on the training data to create cvmodel.

cvmodel = crossval(model,Name,Value) creates a partitioned model with additional options specified by one or more Name,Value pair arguments.

Tips

  • Assess the predictive performance of model on cross-validated data using the "kfold" methods and properties of cvmodel, such as kfoldLoss.

Input Arguments

model

A classification model, produced using fitctree.

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 single quotes (' '). You can specify several name and value pair arguments in any order as Name1,Value1,...,NameN,ValueN.

'CVPartition'

Object of class cvpartition, created by the cvpartition function. crossval splits the data into subsets with cvpartition.

Use only one of these four options at a time: 'KFold', 'Holdout', 'Leaveout', or 'CVPartition'.

'Holdout'

Holdout validation tests the specified fraction of the data, and uses the remaining data for training. Specify a numeric scalar from 0 to 1. Use only one of these four options at a time: 'KFold', 'Holdout', 'Leaveout', or 'CVPartition'.

'KFold'

Number of folds to use in a cross-validated tree, a positive integer.

Use only one of these four options at a time: 'KFold', 'Holdout', 'Leaveout', or 'CVPartition'.

Default: 10

'Leaveout'

Set to 'on' for leave-one-out cross validation.

Use only one of these four options at a time: 'KFold', 'Holdout', 'Leaveout', or 'CVPartition'.

Output Arguments

cvmodel

Partitioned model of class ClassificationPartitionedModel.

Examples

expand all

Create a Cross-Validation Model

Create a classification model for the ionosphere data, then create a cross-validation model. Evaluate the quality the model using kfoldLoss.

load ionosphere
tree = fitctree(X,Y);
cvmodel = crossval(tree);
L = kfoldLoss(cvmodel)
L =
    0.1168

Alternatives

You can create a cross-validation tree directly from the data, instead of creating a decision tree followed by a cross-validation tree. To do so, include one of these five options in fitctree: 'CrossVal', 'KFold', 'Holdout', 'Leaveout', or 'CVPartition'.

See Also

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