#-*- R -*-

library(MASS)
library(class)
library(nnet)

K <- 10

FileName=paste("TestA-C-",K)

#decrease len if you have little memory.

decplot <- function(xp, yp, Z, t, Err=0, N=-1)
{
    plot(Pop[, 1], Pop[, 2], xlab = "x1", ylab = "x2", col=Pop$y+1)
	title(paste(t,K))
	if(N>0) mtext(paste("Error=",100*Err/N,"%"))
    zp <- Z[, 1] - Z[, 2]
    contour(xp, yp, matrix(zp, np), add = T, levels = 0, labex = 0)
    invisible()
}

TrainA1<-read.table("TrainA1.dat")
names(TrainA1)<-c("x1","x2","y")

p <- as.matrix(TrainA1[, -3])
xp <- seq(min(TrainA1$x1), max(TrainA1$x1), length = 50); np <- length(xp)
yp <- seq(min(TrainA1$x2), max(TrainA1$x2), length = 50); 
pt <- expand.grid(x1 = xp, x2 = yp)

par(mfcol=c(2,2))

tp <- TrainA1$y

yhat <- knn(p, p, tp, k = K)
CErr = 0
for( i in 1:50 ) { if( yhat[i] == 0 ) CErr = CErr + 1 }
for( i in 51:100 ) { if( yhat[i] == 1 ) CErr = CErr + 1 }

Z <- knn(p, pt, tp, k = K)
Pop<-TrainA1
decplot(xp, yp, class.ind(Z),"TrainA1 k=", CErr, length(yhat))

TrainA2<-read.table("TrainA2.dat")
names(TrainA2)<-c("x1","x2","y")

p2 <- as.matrix(TrainA2[, -3])
xp <- seq(min(TrainA2$x1), max(TrainA2$x1), length = 50); np <- length(xp)
yp <- seq(min(TrainA2$x2), max(TrainA2$x2), length = 50); 
pt <- expand.grid(x1 = xp, x2 = yp)

yhat2 <- knn(p, p2, tp, k = K)
CErr2 = 0
for( i in 1:50 ) { if( yhat2[i] == 0 ) CErr2 = CErr2 + 1 }
for( i in 51:100 ) { if( yhat2[i] == 1 ) CErr2 = CErr2 + 1 }

Pop<-TrainA2
Z <- knn(p, pt, tp, k = K)
decplot(xp, yp, class.ind(Z),"TrainA2 k=", CErr2, length(yhat2))

TrainA12<-rbind(TrainA1,TrainA2)
p12 <- as.matrix(TrainA12[, -3])

tp12 <- TrainA12$y

yhat12 <- knn(p12, p12, tp12, k = K)
CErr12 = 0
for( i in 1:50 ) { if( yhat12[i] == 0 ) CErr12 = CErr12 + 1 }
for( i in 51:100 ) { if( yhat12[i] == 1 ) CErr12 = CErr12 + 1 }
for( i in 100:150 ) { if( yhat12[i] == 0 ) CErr12 = CErr12 + 1 }
for( i in 151:200 ) { if( yhat12[i] == 1 ) CErr12 = CErr12 + 1 }

xp <- seq(min(TrainA12$x1), max(TrainA12$x1), length = 50); np <- length(xp)
yp <- seq(min(TrainA12$x2), max(TrainA12$x2), length = 50); 
pt <- expand.grid(x1 = xp, x2 = yp)

Pop<-TrainA2
Z <- knn(p12, pt, tp12, k = K)
decplot(xp, yp, class.ind(Z),"TrainA1+A2 k=", CErr12, length(yhat12))

TestA<-read.table("TestA.dat")
names(TestA)<-c("x1","x2")

y <- knn(p12, TestA, tp12, k=K)
write.table(data.frame(TestA,y), FileName, quote=F, col.name=F, row.name=F)

Pop<-TestA
Z <- knn(p12, pt, tp12, k = K)
decplot(xp, yp, class.ind(Z),"TestA k=")