r - 如何更改 ggplot2 geom_raster 中的插值/平滑

Question

是否可以在 geom_raster 中更改插值级别(例如平滑、模糊)？ ?

library(tidyverse)

mtcars %>%
  group_by(carb, hp = cut(mtcars$hp, 3, labels = c("low", "med", "hi"))) %>%
  summarise(mean_mpg = mean(mpg)) %>%
  ggplot(aes(carb, hp)) +
  geom_raster(aes(fill = mean_mpg), interpolate = FALSE) +
  scale_fill_viridis_c(option = "inferno")

我想控制下图中发生的模糊程度:

mtcars %>%
  group_by(carb, hp = cut(mtcars$hp, 3, labels = c("low", "med", "hi"))) %>%
  summarise(mean_mpg = mean(mpg)) %>%
  ggplot(aes(carb, hp)) +
  geom_raster(aes(fill = mean_mpg), interpolate = TRUE) +
  scale_fill_viridis_c(option = "inferno")

我知道如何用 stat_density_2d 做到这一点-- see this post - 但我想通过填充计算值而不是计算密度。

Answer 1

AFAIK，除了打开或关闭它之外，您无法操纵网格函数的插值。相反，ggfx 包允许您使用您选择的“sigma”参数模糊特定图层。下面的例子:

library(tidyverse)
library(ggfx)

mtcars %>%
  group_by(carb, hp = cut(mtcars$hp, 3, labels = c("low", "med", "hi"))) %>%
  summarise(mean_mpg = mean(mpg)) %>%
  ggplot(aes(carb, hp)) +
  with_blur(
    geom_raster(aes(fill = mean_mpg), interpolate = FALSE),
    sigma = 10
  ) +
  scale_fill_viridis_c(option = "inferno")
#> `summarise()` has grouped output by 'carb'. You can override using the `.groups` argument.
#> Warning: Raster pixels are placed at uneven horizontal intervals and will be
#> shifted. Consider using geom_tile() instead.

创建于 2021-08-29 由 reprex package (v2.0.0)