自定义平滑置信区间的计算方式

Question

用于通过loess函数绘制一堆点的geom_smooth估计值以及置信区间。

现在我需要改变计算置信界限的方法（即我需要改变模糊带的形状）。有没有办法在geom_smooth中执行此操作？

或者，如何使用ggplot2模拟它？我怎么能这么模糊乐队？

Answer 1

如果你需要绘制一些不是geom_smooth中任何一个选项的东西，你最好的选择是自己手动拟合模型。

你还没说过你需要什么方法。 但是这里有一个将黄土与家族对称拟合并计算其标准误差的例子。

d <- data.frame(x = rnorm(100), y = rnorm(100))

# The original plot using the default loess method
p <- ggplot(d, aes(x, y)) + geom_smooth(method = 'loess', se = TRUE)

# Fit loess model with family = 'symmetric'
#   Replace the next 2 lines with whatever different method you need
loess_smooth <- loess(d$x ~ d$y, family = 'symmetric')

# Predict the model over the range of data you are interested in.
loess_pred <- predict(loess_smooth, 
                      newdata = seq(min(d$x), max(d$x), length.out = 1000), 
                      se = TRUE)

loess.df <- data.frame(fit = loess_pred$fit, 
                       x =  seq(min(d$x), max(d$x), length.out = 1000), 
                       upper = loess_pred$fit + loess_pred$se.fit, 
                       lower = loess_pred$fit - loess_pred$se.fit)

# plot to compare
p + 
  geom_ribbon(data = loess.df, aes(x = x, y = fit, ymax = upper, ymin = lower), alpha = 0.6) +
  geom_line(data = loess.df, aes(x = x, y = fit))