R/cr.backward.R

In glmpathcr: Fit a Penalized Continuation Ratio Model for Predicting an Ordinal Response

cr.backward <-
function(x,y,weight) {
    yname <- as.character(substitute(y))
    if (!is.factor(y)) 
        y <- factor(y, exclude = NA)
    ylevels <- levels(y)
    kint <- length(ylevels) - 1
    y <- as.numeric(y)
    names<-dimnames(x)[[2]]
    if (length(names)==0) names<-paste("V",1:dim(x)[2],sep="")
    expand<-list()
    for (k in 2:(kint+1)) {    
       expand[[k-1]]<-cbind(y[is.element(y,1:k)], weight[is.element(y, 1:k)], x[is.element(y,1:k),])
       expand[[k-1]][,1]<-ifelse(expand[[k-1]][,1]==k,1,0)
       cp<-matrix(rep(0,dim(expand[[k-1]])[1]*kint),ncol=kint)
       cp[,k-1]<-1
       dimnames(cp)[[2]]<-paste("cp",1:kint,sep="")
       expand[[k-1]]<-cbind(expand[[k-1]],cp)
	   dimnames(expand[[k-1]])[[2]]<-c("y","weight",names,paste("cp",1:kint,sep=""))
    } 
	newx<-expand[[1]]
	for (k in 2:kint)  newx<-rbind(newx,expand[[k]])
    newx
    }