R中的ggplot：重复的多面geom_density和geom_density_ridges结果

Question

ggplot2::geom_density()（带有小平面）和ggridges::geom_density_ridges()的默认设置会产生稍微不同的曲线。如何修改一个或另一个平滑技术以产生相同的结果？

library(tidyverse)
library(ggridges)

# standard density with facet by cyl ----
mtcars %>%
  ggplot(aes(x = mpg)) +
  geom_density(fill = "gray") +
  facet_wrap(. ~ factor(cyl, levels = c(8, 6, 4)), ncol = 1) +
  theme_minimal()

# density ridge with y = cyl ----
mtcars %>%
  ggplot(aes(x = mpg, y = factor(cyl))) +
  geom_density_ridges() +
  theme_minimal()
#> Picking joint bandwidth of 1.38

^{由reprex package（v0.2.1）于2019-04-04创建}

Answer 1

您可以使用geom_density()使用的相同统计信息。

library(tidyverse)
library(ggridges)

# standard density with facet by cyl ----
mtcars %>%
  ggplot(aes(x = mpg)) +
  geom_density(fill = "gray") +
  facet_wrap(. ~ factor(cyl, levels = c(8, 6, 4)), ncol = 1) +
  theme_minimal()

# density ridge with y = cyl ----
mtcars %>%
  ggplot(aes(x = mpg, y = factor(cyl))) +
  geom_density_ridges(stat = "density", aes(height = stat(density))) +
  theme_minimal()

^{由reprex package（v0.2.1）于2019-04-04创建}

或者，您可以使用geom_density_ridges()报告的带宽并将其用于geom_density()（此处为bw = 1.38）。

library(tidyverse)
library(ggridges)

# density ridge with y = cyl ----
mtcars %>%
  ggplot(aes(x = mpg, y = factor(cyl))) +
  geom_density_ridges() +
  theme_minimal()
#> Picking joint bandwidth of 1.38

# standard density with facet by cyl ----
mtcars %>%
  ggplot(aes(x = mpg)) +
  geom_density(fill = "gray", bw = 1.38) +
  facet_wrap(. ~ factor(cyl, levels = c(8, 6, 4)), ncol = 1) +
  theme_minimal()

^{由reprex package（v0.2.1）于2019-04-04创建}

最后两个图看起来略有不同，因为它们具有不同的x轴限制。