R/plot.varianceMapOut.R

In latticeDensity: Density Estimation and Nonparametric Regression on Irregular Regions

#' Plot the standard error map.
#' 
#' Takes as input a varianceMapOut object from the 
#' function varianceMap. This plotting function 
#' makes a countour plot of the non-parametric 
#' regression standard error surface.
#' 
#' @references Julie McIntyre, Ronald P. Barry (2018)  A Lattice-Based 
#' Smoother for Regions with Irregular Boundaries and Holes.  
#' Journal of Computational and Graphical Statistics.  In Press.
#' @param x An object of type varianceMapOut returned by varianceMap.
#' @param \dots Other arguments to be passed to functions plot, 
#' points, lines.
#' @author Ronald P. Barry
#' @examples 
#' data(nparExample)
#' attach(nparExample)
#' plot.new()
#' #  Simulate a response variable
#' index1 <- (grid2[,2]<0.8)|(grid2[,1]>0.6)
#' Z <- rep(NA,length(grid2[,1]))
#' n1 <- sum(index1)
#' n2 <- sum(!index1)
#' Z[index1] <- 3*grid2[index1,1] + 4 + rnorm(n1,0,sd=0.4)
#' Z[!index1] <- -2*grid2[!index1,1] + 4 + rnorm(n2,0,sd=0.4)
#' #
#' plot(polygon2,type="n")
#'
#' polygon(polygon2)
#' points(grid2,pch=19,cex=0.5,xlim=c(-0.1,1))
#' text(grid2,labels=round(Z,1),pos=4,cex=0.5)
#' #
#' nodeFillingOutput <- nodeFilling(poly=polygon2, node_spacing=0.025)
#' plot(nodeFillingOutput)
#' formLatticeOutput <- formLattice(nodeFillingOutput)
#' plot(formLatticeOutput)
#' hold <- crossvalNparReg(formLatticeOutput,Z,
#'                        PointPattern=grid2,M=0.5,max_steps = 25)
#' var_map <- varianceMap(formLatticeOutput,Z,
#'              PointPattern=grid2,M=0.5,k=hold$k)
#' plot(var_map)
#' 
#' @import utils
#' @import graphics
#' @import stats
#' @export
#' @method plot varianceMapOut
plot.varianceMapOut <-
  function(x,...){
    #
    if(class(x) != "varianceMapOut"){
      stop("This function only plots objects of type varianceMapOut")
    }
    EW_locs <- as.vector(x$EW_locs)
    NS_locs <- as.vector(x$NS_locs)
    SE_map <- as.vector(x$SE_map)
    boundaryPoly <- as.matrix(x$boundaryPoly)
    hole_list <- x$hole_list
    big_matrix <- 
          matrix(nrow=length(EW_locs),ncol=length(NS_locs),SE_map)
    contour(x=EW_locs,y=NS_locs,z=big_matrix,...)
    lines(rbind(boundaryPoly,boundaryPoly[1,]),...)
    n_hole <- length(hole_list)
    for(i in 1:n_hole){
      lines(rbind(hole_list[[i]],hole_list[[i]][1,]),...)
    }
  }