##########################
## Voronoi
##########################
library(class)

Voronoi <- function(data, tp, test.dim, Xlim, Ylim){ 

   res.g <- f.create.grid(cbind(Xlim, Ylim), test.dim)
   xp <- res.g[[1]]
   yp <- res.g[[2]]
   zp <- res.g[[3]]
   numb.classes <- length(levels(factor(tp)))
           # Display classes as text
   plot(data[,1], data[,2], type="n", xlab="X", ylab = "Y", xlim=Xlim,ylim=Ylim)
   text(data[,1], data[,2], as.character(tp))
        # Compute the nearest neighbour for the test points (grid)
   Z <- knn(data, zp, tp, k = 1)
        # For all cases in which the nn is 0 the contour map has a 1 else 0
        # Draw the contour at 0.5 (add=T means add to current plot).
   for (c in 1:numb.classes) {
      contour(xp, yp, matrix(as.numeric(Z==(c-1)), length(xp), length(yp)), 
                    add=T, levels=0.5, labex=0, col="blue")
   }
}


testVoronoi <- function() {
   x.data.size <- 200
   y.data.size <- 200

   pos <- matrix(c(-1,1,-1,-1,1,2,1,-1), 4, 2, byrow=T)
   class <-  matrix(c(0,1,2,3), 4, byrow=TRUE)
   Voronoi (pos, class, c(x.data.size, y.data.size), c(-2,2),c(-2,2))

   pos <- matrix(c(-1,1,-1,-1,1,2,1,-1,0,0), 5, 2, byrow=T)
   class <-  matrix(c(0,1,2,3,4), 5, byrow=TRUE)
   Voronoi (pos, class, c(x.data.size, y.data.size), c(-2,2),c(-2,2))

   pos <- matrix(c(-2,1,-1,-1,1,2,1,-1,0,0), 5, 2, byrow=T)
   class <-  matrix(c(0,1,2,3,4), 5, byrow=TRUE)
   Voronoi (pos, class, c(x.data.size, y.data.size), c(-2,2),c(-2,2))

   pos <- matrix(c(-2,1, -1,-1, 1,2, 1,-1, 0,0, .5,-.5, 1,.5), 7, 2, byrow=T)
   class <-  matrix(c(0,1,2,3,4,5,6), 7, byrow=TRUE)
   Voronoi (pos, class, c(x.data.size, y.data.size), c(-2,2),c(-2,2))
}