rgp (version 0.4-1)

buildingBlock: Support for GP buidling blocks

Description

Building blocks are a means for protecting expression subtrees from modification through variation operators. Often, certain functional units, represented as expression subtrees in GP individuals, should stay intact during evolutionary search. Building blocks at the leafs of expressions can be introduced by adding them to the input variable set. Support for building blocks is planned for a future release of RGP.

Usage

buildingBlock(expr, hardness = 1)
buildingBlockq(expr, hardness = 1)

Arguments

expr

The expresion to transform to a building block.

hardness

The strength of the protection against varition inside the building block. Must be a numeric in the interval [0.0, 1.0]. A hardness of 1.0 (the default) means that the building block will never be subject to variation.

Value

A building block.

Details

buildingBlock transforms an R expression to a building block to be used as an element of the input variable (or function) set. The parameter hardness (a numerical value in the interval [0.0 , 1.0]) determines the protection strength against variation inside the building building block. When hardness is set to 1.0 (the default), the building block will never be subject to variaton through mutation or crossover. buildingBlockq is equivaltent to buildingBlock, but quotes it's argument expr first.