[R] accessing the "address" of items in a recursive list

[phlow]

j daniel wrote:
> 
> 
> I would like to print the "address" of the smaller dendrograms on the edge
> similar to this:
> 
> addr <- function(n) {
>       if(!is.leaf(n)) {
>         attr(n, "edgetext") <- paste("height of",(attr(n,"height"))
>       }
>       n
> }
> labeledDends <- dendrapply(dend, addr)
> 
> Where "i,j,k" is printed instead of "height".  But I have not been able to
> figure out how to ask each dendrogram its address within the dendrapply
> function.  Can anyone help me with this?
> 
> 
Hi!

Load the following four functions into R and execute this (assuming your
dendrogram is in variable 'dend')

newdend <- dendrapplyGlobal(dend,
"height",function(x){names(x)},attrNameTo="edgetext")



#From the specified dendrogram X a vector of all values of the specified 
#node attribute is extracted, modified by the function FUN and a new
#dendrogram is created using the new values for the attribute. Optionally,
#a different attribute can be set using 'attrNameTo'
dendrapplyGlobal <- function(X,attrName,FUN,...,attrNameTo=NULL) {
	if (is.null(attrNameTo)) {
		attrNameTo <- attrName
	}
	funcGet <- function(x){
		attr(x,attrName)
	}
	funcSet <- function(x,value){
		attr(x,attrNameTo) <- value
		return(x)
	}
	values <- dendrapplyToVector(X,funcGet)
	values <- FUN(values,...)
	ret <- dendrapplyFromVector(X,values,funcSet)
	return(ret)
}

#Traverses the dendrogram in postorder and applies FUN to each node.
#The result of each evaluation is stored in the resulting array.
#Additional arguments to FUN can be passed as ...
#The names attribute of the resulting vector is the 'path' to each node.
#This implementation is based on dendrapply(graphics).
dendrapplyToVector <- function(X,FUN,...) {
	FUN <- match.fun(FUN)
	    if (!inherits(X, "dendrogram")) 
	        stop("'X' is not a dendrogram")
	    Napply <- function(d,path="") {
	    	if (is.leaf(d)) {
	    		ret <- c(FUN(d,...))
	    		names(ret)[1] <- substr(path,start=1,stop=nchar(path)-1)
	    		return(ret)
	    	} 
	    	ret <- vector()
	    	for (j in seq_along(d)) {
	    		addr <- paste(path,j,".",sep="")
	    		ret <- append(ret,Napply(d[[j]],addr))
	    	}
	    	ret <- append(ret,FUN(d,...))
	    	names(ret)[length(ret)] <- substr(path,start=1,stop=nchar(path)-1)
	        return(ret)
	    }
    Napply(X)
}

#Traverses the dendrogram X in postorder and constructs a new dendrogram
using
#the specified function FUN and vector parVec. Each element of parVec must
#relate to a node in X, which is the case if parVec was created using
#dendrapplyToVector().
#Additional arguments to FUN can be passed as ...
#This implementation is based on dendrapply(graphics).
dendrapplyFromVector <- function(X,parVec,FUN,...) {
	FUN <- match.fun(FUN)
	    if (!inherits(X, "dendrogram")) 
	        stop("'X' is not a dendrogram")
	    Napply <- function(d,v) {
	    	if (is.leaf(d)) {
	    		ret <- FUN(d,v,...)
	    		return(ret)
	    	} else {
	    		ret <- d
                        if (!is.list(ret)) 
	                	ret <- as.list(ret)
	                i <- 1
	    		for (j in seq_along(d)) {
	    			childrenCount <- getDendrogramNodeCount(d[[j]])
	    			indices <- i:(i+childrenCount-1)
	    			ret[[j]] <- Napply(d[[j]],v[indices])
	    			i <- i + childrenCount
	    		}
	    		ret <- FUN(ret,v[i],...)
	    	}
	        return(ret)
	    }
    Napply(X,parVec)
}

#Returns the number of nodes in a dendrogram.
getDendrogramNodeCount <- function(dend) {
	if (!is.leaf(dend)){
		childrenSum <- 0
		for (child in dend) {
			childrenSum <- childrenSum + getDendrogramNodeCount(child)
		}
		return(childrenSum+1)
	} 
	return(1)
}


hth,
Florian

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