exprso (version 0.1.8)

doMulti: Perform "1 vs. all" Task

Description

A function to execute multiple "1 vs. all" binary tasks.

Usage

doMulti(object, top, method, ...)

# S4 method for ExprsMulti doMulti(object, top, method, ...)

Arguments

object

Specifies the ExprsArray object to undergo feature selection.

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.

method

A character string. The ExprsBinary method to execute multiple times.

...

Arguments passed to the respective wrapped function.

Value

A list of the results given by method.

Methods (by class)

  • ExprsMulti: Method to execute multiple "1 vs. all" binary tasks.

Details

doMulti depends on the total number of levels in the $defineCase factor. If a training set is missing any one of the factor levels (e.g., owing to random cuts during cross-validation), the ExprsModule component that would refer to that class label gets replaced with an NA placeholder. This NA placeholder gets handled as a special case when predicting with an ExprsModule.

During ExprsModule class prediction, the absence of a class during training (i.e., an NA placeholder) will prevent an ExprsModule object from possibly predicting that class in a validation set. Rather, an ExprsModule can only make predictions about class labels that it "knows". However, all "unknown" classes in the validation set (i.e., those missing from the training set) still impact metrics of classifier performance.

An ExprsModule object can only make predictions on an ExprsMulti object with the same number of recorded class labels (i.e., the total number of levels in the $defineCase factor). As with all functions included in this package, all ties get broken using probability weights proportional to the relative class frequencies in the training set.

See Also

fs build doMulti exprso-predict plCV plGrid plGridMulti plMonteCarlo plNested