exprso (version 0.1.7)

plCV: Perform Simple Cross-Validation

Description

Calculates v-fold or leave-one-out cross-validation without selecting a new set of features with each fold.

Usage

plCV(array, top, how, fold, ...)

Arguments

array
Specifies the ExprsArray object to undergo cross-validation.
top
A numeric scalar or character vector. A numeric scalar indicates the number of top features that should undergo feature selection. A character vector indicates specifically which features by name should undergo feature selection. Set top = 0 to include all features. A numeric vector can also be used to indicate specific features by location, similar to a character vector.
how
A character string. Specifies the build method to iterate.
fold
A numeric scalar. Specifies the number of folds for cross-validation. Set fold = 0 to perform leave-one-out cross-validation.
...
Arguments passed to the how method.

Value

A numeric scalar. The cross-validation accuracy.

Details

plCV performs v-fold or leave-one-out cross-validation for an ExprsArray object. The argument fold specifies the number of v-folds to use during cross-validation. Set fold = 0 to perform leave-one-out cross-validation. This approach to cross-validation will work for ExprsBinary and ExprsMulti objects alike. The peformance metric used to measure cross-validation accuracy is the acc slot returned by calcStats.

This type of cross-validation is most appropriate if the ExprsArray has not undergone any prior feature selection. However, it may also have a role as an unbiased guide to parameter selection when embedded in plGrid. If using cross-validation in lieu of an independent test set in the setting of one or more feature selection methods, consider using a more "sophisticated" form of cross-validation as implemented in plMonteCarlo or plNested.

When calculating classifier performance with calcStats, this function forces aucSkip = TRUE and plotSkip = TRUE.

See Also

fs build doMulti exprso-predict plCV plGrid plGridMulti plMonteCarlo plNested