在图形设备的子图形中组合 base 和 ggplot 图形

Question

我想使用 base R 生成一组图，每个图都有自己的基于 ggplot 的插入图，向右对齐，略低于右上角，以便我可以在上面添加一些文本。像这样的东西（我用 MS Paint 手绘了 ggplot 插入）。

我认为这可能使用 viewports - 类似于 this 问题。

# ggplot code for inserts
library(tidyverse)
g1 <- ggplot(data = mtcars, mapping = aes(x = cyl)) +
  geom_density(colour = "red") +
  theme_void()
g2 <- ggplot(data = mtcars, mapping = aes(x = disp)) +
  geom_density(colour = "red") +
  theme_void()
g3 <- ggplot(data = mtcars, mapping = aes(x = hp)) +
  geom_density(colour = "red") +
  theme_void()
g4 <- ggplot(data = mtcars, mapping = aes(x = drat)) +
  geom_density(colour = "red") +
  theme_void()
g5 <- ggplot(data = mtcars, mapping = aes(x = wt)) +
  geom_density(colour = "red") +
  theme_void()
g6 <- ggplot(data = mtcars, mapping = aes(x = qsec)) +
  geom_density(colour = "red") +
  theme_void()

我试过使用视口函数，但是，我无法相对于每个子图形放置插入（我认为它们都是基于整体图形设备放置的）...

library(grid)
par(mfrow = c(2, 3))
vps <- baseViewports()
plot(x = mtcars$mpg, y = mtcars$cyl)
pushViewport(vps$figure)
print(g1, vp = viewport(height = unit(0.2, "npc"), width = unit(0.2, "npc"), x = 1, y = 0.8, just  = 1))
plot(x = mtcars$mpg, y = mtcars$disp)
pushViewport(vps$figure)
# upViewport()
# popViewport()
print(g2, vp = viewport(height = unit(0.2, "npc"), width = unit(0.2, "npc"), x = 1, y = 0.8, just  = 1))
plot(x = mtcars$mpg, y = mtcars$hp)
print(g3, vp = viewport(height = unit(0.2, "npc"), width = unit(0.2, "npc"), x = 1, y = 0.8, just  = 1))
plot(x = mtcars$mpg, y = mtcars$drat)
print(g4, vp = viewport(height = unit(0.2, "npc"), width = unit(0.2, "npc"), x = 1, y = 0.8, just  = 1))
plot(x = mtcars$mpg, y = mtcars$wt)
print(g5, vp = viewport(height = unit(0.2, "npc"), width = unit(0.2, "npc"), x = 1, y = 0.8, just  = 1))
plot(x = mtcars$mpg, y = mtcars$qsec)
print(g6, vp = viewport(height = unit(0.2, "npc"), width = unit(0.2, "npc"), x = 1, y = 0.8, just  = 1))

Answer 1

一个解决方案（不涉及在您想要制作的地块上做出妥协）是使用 viewpoint() 中的 layout 参数为子地块设置一个网格，覆盖par(mfrow)/par(mfcol) 网格。

将视点网格设置为 par(mfrow) 维度的倍数可以让您将子图很好地放置在所需的网格位置。视点网格的比例将决定子图的大小 - 因此更大的网格将导致更小的子图。

# base R plots
par(mfrow = c(2, 3))
plot(x = mtcars$mpg, y = mtcars$cyl)
plot(x = mtcars$mpg, y = mtcars$disp)
plot(x = mtcars$mpg, y = mtcars$hp)
plot(x = mtcars$mpg, y = mtcars$drat)
plot(x = mtcars$mpg, y = mtcars$wt)
plot(x = mtcars$mpg, y = mtcars$qsec)

# set up viewpoint grid
library(grid)
pushViewport(viewport(layout=grid.layout(20, 30)))

# add ggplot subplots (code for these objects in question) at `layout.pos.row`, `layout.pos.col` 
print(g1, vp = viewport(height = unit(0.2, "npc"), width = unit(0.05, "npc"), 
                        layout.pos.row = 2, layout.pos.col = 9))
print(g2, vp = viewport(height = unit(0.2, "npc"), width = unit(0.05, "npc"), 
                        layout.pos.row = 2, layout.pos.col = 19))
print(g3, vp = viewport(height = unit(0.2, "npc"), width = unit(0.05, "npc"), 
                        layout.pos.row = 2, layout.pos.col = 29))
print(g4, vp = viewport(height = unit(0.2, "npc"), width = unit(0.05, "npc"), 
                        layout.pos.row = 12, layout.pos.col = 9))
print(g5, vp = viewport(height = unit(0.2, "npc"), width = unit(0.05, "npc"), 
                        layout.pos.row = 12, layout.pos.col = 19))
print(g6, vp = viewport(height = unit(0.2, "npc"), width = unit(0.05, "npc"), 
                        layout.pos.row = 12, layout.pos.col = 29))

如果您有简单的基本 R 图，那么另一种方法是使用 ggplotify 将基本图转换为 ggplot，然后使用 cowplot 或 patchwork 进行放置。我无法为我想要的图工作，它使用比上面虚拟示例中的更复杂的一组绘图函数（在 base R 中）。

在图形设备的子图形中组合 base 和 ggplot 图形

Combine base and ggplot graphics in sub figures of graphic device

plot

r

viewport

ggplot2