library(class)
library(MASS)
library(nnet)
#Funciones auxiliares
predplot <- function(object, main="", len = 100, ...)
{
    plot(Cushings[,1], Cushings[,2], type="n",
         xlab = "Tetrahydrocortisone", ylab = "Pregnanetriol", main = main)
    for(il in 1:4) {
        set <- Cushings$Type==levels(Cushings$Type)[il]
        text(Cushings[set, 1], Cushings[set, 2],
             labels=as.character(Cushings$Type[set])) }
    xp <- seq(0, 60, length=len)
    yp <- seq(0, 20, length=len)
    cushT <- expand.grid(Tetrahydrocortisone = xp,
                         Pregnanetriol = yp)
    Z <- predict(object, cushT, ...); zp <- as.numeric(Z$class)
    zp <- Z$post[,3] - pmax(Z$post[,2], Z$post[,1])
    contour(xp, yp, matrix(zp, len),
            add = T, levels=0,drawlabels=FALSE)
    zp <- Z$post[,1] - pmax(Z$post[,2], Z$post[,3])
    contour(xp, yp, matrix(zp, len),
            add = T, levels=0,drawlabels=FALSE)
    invisible()
}

cushplot <- function(xp, yp, Z)
{
    plot(Cushings[, 1], Cushings[, 2], ylim=c(0,20),type = "n",
         xlab = "Tetrahydrocortisone", ylab = "Pregnanetriol")
    for(il in 1:4) {
        set <- Cushings$Type==levels(Cushings$Type)[il]
        text(Cushings[set, 1], Cushings[set, 2],
             labels = as.character(Cushings$Type[set])) }
    zp <- Z[, 3] - pmax(Z[, 2], Z[, 1])
    contour(xp,yp, matrix(zp, np),
            add = T, levels = 0,drawlabels=FALSE)
    zp <- Z[, 1] - pmax(Z[, 2], Z[, 3])
    contour(xp, yp, matrix(zp, np),
            add = T, levels = 0, drawlabels=FALSE)
    invisible()
}

xp <- seq(0, 60, length = 50)
yp <- seq(0, 20, length = 50)
np <- length(xp)
cushT <- expand.grid(Tetrahydrocortisone = xp,
                     Pregnanetriol = yp)

#Grafica de knn-1
tp <- Cushings$Type[1:21, drop = T]
Z <- knn(Cushings[1:21,-3], cushT, tp)
win.graph()
cushplot(xp, yp, class.ind(Z))
color=c("red","blue","green")[as.factor(Z)]
points(cushT[,1],cushT[,2],col=color)
title("Grafica de las fronteras de knn-1")
#Grafica de knn-3
Z <- knn(Cushings[1:21, -3], cushT, tp, k = 3)
win.graph()
cushplot(xp, yp, class.ind(Z))
color=c("red","blue","green")[as.factor(Z)]
points(cushT[,1],cushT[,2],col=color)
title("Grafica de las fronteras de knn-3")
#Grafica de LDA
tp <- Cushings$Type[1:21, drop = T]
cush.lda <- lda(as.matrix(Cushings[1:21,-3]), tp)
win.graph()
predplot(cush.lda, "Grafica de las fronteras de LDA",len=50)