R: Computation of a negative region

BC.negative.reg.RST {RoughSets} | R Documentation

## Computation of a negative region

### Description

This function implements a fundamental part of RST: computation of a negative region and the degree of dependency. This function can be used as a basic building block for development of other RST-based methods. A more detailed explanation of this notion can be found in `A.Introduction-RoughSets`.

### Usage

    BC.negative.reg.RST(decision.table, roughset)

### Arguments

`decision.table` | an object inheriting from the `"DecisionTable"` class, which represents a decision system. See `SF.asDecisionTable`.
`roughset` | an object inheriting from the `"LowerUpperApproximation"` class, which represents lower and upper approximations of decision classes in the data. Such objects are typically produced by calling the `BC.LU.approximation.RST` function.

### Value

An object of a class `"NegativeRegion"` which is a list with the following components:

- `negative.reg`: an integer vector containing indices of data instances belonging to the boundary region,

- `degree.dependency`: a numeric value giving the degree of dependency,

- `type.model`: a varacter vector identifying the utilized model. In this case, it is `"RST"` which means the rough set theory.

### Author(s)

Dariusz Jankowski, Andrzej Janusz

### References

Z. Pawlak, "Rough Sets", International Journal of Computer and Information Sciences, vol. 11, no. 5, p. 341 - 356 (1982).

### See Also

`BC.IND.relation.RST`, `BC.LU.approximation.RST`, `BC.LU.approximation.FRST`

### Examples

    ########################################################
    data(RoughSetData)
    hiring.data <- RoughSetData$hiring.dt

    ## We select a single attribute for computation of indiscernibility classes:
    A <- c(2)

    ## compute the indiscernibility classes:
    IND.A <- BC.IND.relation.RST(hiring.data, feature.set = A)

    ## compute the lower and upper approximation:
    roughset <- BC.LU.approximation.RST(hiring.data, IND.A)

    ## get the boundary region:
    pos.negative = BC.negative.reg.RST(hiring.data, roughset)
    pos.negative

[Package RoughSets version 1.3-7 Index]