将 Cook 的距离级别添加到 ggplot2

Question

如何在第一个图中添加显示库克距离的红色虚线轮廓线 到第二个情节使用ggplot和ggfortify？

使用的代码：

library(ggfortify)
model <- glm(mpg ~ wt, data = mtcars, family = gaussian())
plot(model, which = 5) # first plot
autoplot(model, which = 5) # second plot

我认为geom_contour可以添加，但我不知道用于计算库克距离线的公式。

Answer 1

经过一些研究，我设法绘制了level使用公式的轮廓sqrt(level * length(coef(model)) * (1 - leverage)/leverage)，这是 R 用来绘制其轮廓的plot.lm。不过，我使用的方法肯定可以改进。

library(ggplot2)
library(ggfortify)
model <- glm(mpg ~ wt, data = mtcars, family = gaussian())

cd_cont_pos <- function(leverage, level, model) {sqrt(level*length(coef(model))*(1-leverage)/leverage)}
cd_cont_neg <- function(leverage, level, model) {-cd_cont_pos(leverage, level, model)}

autoplot(model, which = 5) +
    stat_function(fun = cd_cont_pos, args = list(level = 0.5, model = model), xlim = c(0, 0.25), lty = 2, colour = "red") +
    stat_function(fun = cd_cont_neg, args = list(level = 0.5, model = model), xlim = c(0, 0.25), lty = 2, colour = "red") +
    scale_y_continuous(limits = c(-2, 2.5))