chooseNode {xegaDerivationTrees}

Selects an attributed node in an attributed node list randomly.

Description

chooseNode() returns a random attributed node from an attributed node list

Usage

chooseNode(ANL)

Arguments

ANL

Attributed node list.

Details

An attributed node has the following elements:

• ID

• NonTerminal

• Pos

• Depth

• Rdepth

• subtreedepth

• node$Index

These elements can be used e.g.

• for inserting and extracting subtrees (Pos or node$Index),

• for checking the feasibility of subtree substitution (ID),

• for checking depth bounds (Depth, RDepth, and subtreedepth), ...

Value

Attributed node.

See Also

Other Random Choice: chooseRule()

Examples

g<-compileBNF(booleanGrammar())
a<-randomDerivationTree(g$Start, g)
b<-treeANL(a, g$ST)
c<-chooseNode(b$ANL)