RoughSets (version 1.3-7)

FS.feature.subset.computation: The superreduct computation based on RST and FRST

Description

This function is a wrapper for computing different types of decision superreducts (i.e. attribute subsets which do not lose any information regarding the decisions but are not require to be irreducable).

Usage

FS.feature.subset.computation(decision.table,
  method = "greedy.heuristic.superreduct", ...)

Value

A class "FeatureSubset".

Arguments

decision.table

an object of a "DecisionTable" class representing a decision table. See SF.asDecisionTable.

method

a character representing the type of a method to use for computations. See in Section Details.

...

other parameters corresponding to the chosen method.

Author

Andrzej Janusz

Details

Currently, there are implemented three methods that can be used with this function:

• "greedy.heuristic.superreduct": it is a greedy heuristic method which employs several quality measures from RST. See FS.greedy.heuristic.superreduct.RST.

• "quickreduct.frst": it is a feature selection function based on the fuzzy QuickReduct algorithm on FRST. See FS.quickreduct.FRST.

• "quickreduct.rst": it is a feature selection function based on the RST QuickReduct algorithm. See FS.quickreduct.RST.

These methods can be selected by assigning an appropriate value of the parameter method. Additionally, SF.applyDecTable is provided to generate the new decision table.

See Also

FS.greedy.heuristic.superreduct.RST, FS.quickreduct.RST, FS.quickreduct.FRST.

Examples

###############################################################
## Example 1: generate reduct and new decision table using RST
###############################################################
data(RoughSetData)
decision.table <- RoughSetData$hiring.dt

## generate single superreduct
res.1 <- FS.feature.subset.computation(decision.table,
                                       method = "quickreduct.rst")

## generate new decision table according to the reduct
new.decTable <- SF.applyDecTable(decision.table, res.1)

###############################################################
## Example 2: generate reduct and new decision table using FRST
###############################################################
data(RoughSetData)
decision.table <- RoughSetData$housing7.dt

## generate single superreduct
res.2 <- FS.feature.subset.computation(decision.table,
                                       method = "quickreduct.frst")

## generate new decision table according to the reduct
new.decTable <- SF.applyDecTable(decision.table, res.2)