R 在我的二元核回归平滑函数中获得0的fhat值

我在下面编写了一个内核回归平滑函数

#simulated data: b0 + b1x1 + b2x2 + e
x1 <- runif(100)
x2 <- runif(100)
y <- 5 + 7 * x1 + 5 * x2 + rnorm(100,0,.1)
sample <- cbind(x1, x2, y)
sample <- as.data.frame(sample)

Kregsmooth2 <- function(sample, h){
  output <- matrix(0, nrow = 100, ncol = 100)
  grid.x1 <- seq(min(sample$x1), max(sample$x1), length.out = 100)
  grid.x2 <- seq(min(sample$x2), max(sample$x2), length.out = 100)
  for (j in 1:length(grid.x2)){
    for (i in 1:length(grid.x1)){
      output[i,j] <- sum(sample$y * dnorm((grid.x1[i]-sample$x1)/h)) * sum(sample$y * dnorm((grid.x2[j]-sample$x2)/h)) / (sum(dnorm((grid.x1[i]-sample$x1)/h)) * sum(dnorm((grid.x2[j]-sample$x2)/h)))
    }
  return(list(x1 = grid.x1, x2 = grid.x2, output=output))
  }
}

fit <- Kregsmooth2(sample, 1)
fit

模拟数据：b0+b1x1+b2x2+e

---

x1您将

return

放入

j

-循环中。将其向下移动到一个下方

}