R/extspace_dat.R

In whcsu/sfse: Random Survival Forest with Space Extensions (short line)

##' space extension for training data
##' @export
extspace_dat <-
function(xdata)
{
  #FIRST convert all catergorical values (factors) into binary values
  #0+ to del Intercept produced by model.matrix
  xdata=model.matrix(~0+.,as.data.frame(xdata))
  
  
  # candidate variable for genereation
  p=ncol(xdata)
  d=p
  ncomb <- combn(p, 2)
  ncombsub <- ncomb[, sample(choose(p,2), d)]
  
  newx<- vector(mode = "list", length = d)
  newx<-NULL
  new_names <- paste("newvar", 1:d, sep="_")
  
  for (i in 1:p){
    newx=cbind(newx,xdata[,ncombsub[2,i]]-xdata[,ncombsub[1,i]])
  }
  colnames(newx)<-new_names
#random choose d new features
  # choosing according to some log-rank standard
  
  newxdata=cbind(xdata,newx)
  return (list(newxdata=newxdata,ncombsub=ncombsub))
}