r - 在拼凑的主标题和情节标题之间添加图例

Question

是否可以使用拼凑而成的“主要”标题下方和情节标题上方的图例？

library(ggplot2)
library(patchwork)

p1 <- ggplot(mtcars, aes(disp, wt, color = factor(gear))) + 
    geom_point() + 
    labs(title = "first plot title")
p2 <- ggplot(mtcars, aes(drat, qsec, color = factor(gear))) + 
    geom_point() + 
    labs(title = "second plot title")

(p1+p2) + 
    plot_layout(guides = "collect") + 
    plot_annotation(title = "main title") & 
    theme(legend.position = "top")

Answer 1

有点破解，提取图例然后将其绘制在顶部：

# get the legend
l <- cowplot::get_legend(p1 + theme(legend.position = "top"))

(cowplot::plot_grid(l) / (p1 + p2)) + 
  plot_layout(heights = unit(c(1, 5), "cm")) +
  plot_annotation(title = "main title") &
  theme(legend.position = "none")