A K-Nearest neighbor curve fitting function.

knnCont.R

knnCont <- function(X, y, k = 4){
  
  y <- y[order(X)]
  X <- sort(X)
  x.out <- vector()
  y.out <- vector()
  for(x in 1:(length(X)-(k-1))){
    
    x.out <- c(x.out,mean(X[x:(x+(k-1))]))
    y.out <- c(y.out,mean(y[x:(x+(k-1))]))
  }
  return(cbind(x.out,y.out))
}


X <- runif(1000,0,10)
y <- cbind(rep(1,length(X)),X)%*%c(1,2) + rnorm(1000,0,1)
y <- sin(X) + rnorm(1000,0,.1)
test <- knnCont(X,y,k=100)
plot(X,y)
lines(test,col=2)