阻止 geom_密度_ridges 显示不存在的尾部值

当我使用geom_density_ridges()，该图通常最终会显示数据中不存在的值的长尾。

这是一个例子：

library(tidyverse)
library(ggridges)

data("lincoln_weather")

# Remove all negative values for "Minimum Temperature"
d <- lincoln_weather[lincoln_weather$`Min Temperature [F]`>=0,]

ggplot(d, aes(`Min Temperature [F]`, Month)) +
  geom_density_ridges(rel_min_height=.01)

As you can see, January, February, and December all show negative temperatures, but there are no negative values in the data at all.

当然，我可以对 x 轴添加限制，但这并不能解决问题，因为它只是截断了现有的错误密度。

ggplot(d, aes(`Min Temperature [F]`, Month)) +
  geom_density_ridges(rel_min_height=.01) +
  xlim(0,80)

Now the plot makes it look like there are zero values for January and February (there are none). It also makes it look like 0 degrees happened often in December, when in reality there was only 1 such day.

我怎样才能解决这个问题？

一种选择是使用stat_density()代替stat_density_ridges()。有一些事情stat_density()不能做的事情，例如绘制垂直线或重叠点，但另一方面它可以做一些事情stat_density_ridges()不能这样做，例如将分布修剪到数据范围。

# Remove all negative values for "Minimum Temperature"
d <- lincoln_weather[lincoln_weather$`Min Temperature [F]`>=0,]

ggplot(d, aes(`Min Temperature [F]`, Month, group = Month, height = ..density..)) +
  geom_density_ridges(stat = "density", trim = TRUE)

作为替代方案，您可以画一个点地毯，也许这也能满足您的目的或更好：

ggplot(d, aes(`Min Temperature [F]`, Month)) +
  geom_density_ridges(rel_min_height = 0.01, jittered_points = TRUE,
                      position = position_points_jitter(width = 0.5, height = 0),
                      point_shape = "|", point_size = 2,
                      alpha = 0.7)

注意：这两种方法目前无法组合，这需要对统计代码进行一些修改。