xegaDerivationTrees (version 1.0.0.6)

filterANL: Filter an Attributed Node List (ANL) of a derivation tree by depth.

Description

filterANL() deletes all nodes whose depth node$Depth is less than minb and larger than maxb from the ANL. However, if the resulting list is empty, the original ANL is returned.

Usage

filterANL(ANL, minb = 1, maxb = 3)

Value

An attributed node list with nodes whose depths are in

minb:maxb. Each node is represented as a list of the following attributes:

• Node$ID: Id in the symbol table ST.

• Node$NonTerminal: Is the symbol a non-terminal?

• Node$Pos: Position in the trail.

• Node$Depth: Depth of node.

• Node$Rdepth: Residual depth for expansion.

• Node$subtreedepth: Depth of subtree starting here.

• Node$Index: R index of the node in the derivation tree. Allows fast tree extraction and insertion.

Arguments

ANL

Attributed node list.

minb

Integer.

maxb

Integer.

Details

An attributed node has the following elements:

• $ID: Id in the symbol table ST.

• $NonTerminal: Is the symbol a non-terminal?

• $Pos: Position in the trail.

• $Depth: Depth of node.

• $Rdepth: Residual depth for expansion.

• $subtreedepth: Depth of subtree starting here.

• $Index: R index of the node in the derivation tree. Allows fast tree extraction and insertion.

See Also

Other Access Tree Parts: filterANLid(), treeANL(), treeChildren(), treeRoot()

Examples

g<-compileBNF(booleanGrammar())
set.seed(111)
a<-randomDerivationTree(g$Start, g, maxdepth=10)
b<-treeANL(a, g$ST)
c<-filterANL(b, minb=1, maxb=3)
d<-filterANL(b, minb=3, maxb=5)
e<-filterANL(b, minb=14, maxb=15)
f<-filterANL(b, minb=13, maxb=15)