r - 在标题中插入图像并将其大小调整为字体大小

Question

问题

我想在我的ggplot.

到目前为止，我发现这个解决方案使用了一些gtablehacking。但是这个解决方案对我来说有点不可行，因为我想在图像之前和之后添加文本。此外，它不会将图像大小调整为标题的实际字体大小。

library(tidyverse)
library(magick)
library(grid)
library(gtable)

ggplot(iris, 
       aes(x = Sepal.Length, y = Sepal.Width)) +
  geom_point() +
  theme(plot.caption = element_text(hjust=0, 
                                    size = 10)) +
  labs(caption = "\uA9 *INSERT MY COMPANY LOGO HERE* My fabulous company, 2019")

my_logo <- image_read("https://upload.wikimedia.org/wikipedia/commons/3/3e/Phalaenopsis_JPEG.png")
print(my_logo)

目标

我想要达到的就是这个。请注意，徽标的 ( my_logo) 垂直大小等于标题的字体大小。

标签： rggplot2gridgtable

Answer 1

您链接到的答案提供了所有成分，

library(ggplot2)
library(grid)
library(dplyr)
library(gtable)

lg <- textGrob(label = "\uA9", x = unit(0, "npc"), just = "left")
rg <- textGrob(label = "My fabulous company, 2019", x = unit(0, "npc"), just = "left")
mg <- png::readPNG(system.file("img", "Rlogo.png", package="png")) %>%
  rasterGrob(interpolate = TRUE, height = grobHeight(rg))

p <- ggplot(mtcars, aes(wt, mpg)) + 
  geom_point() +
  labs(caption="") # to create space for title

# convert to grob
gt <- ggplotGrob(p)

# create new title as a tableGrob with separate cells for image & text
new.title <- gtable_row('caption', grobs = list(lg,mg,rg),
                        widths = unit.c(grobWidth(lg), grobWidth(mg), unit(1,"null")), 
                        height=unit(1,"null")) %>%
  # optional: adda fixed amt of space between image & text
  gtable_add_col_space(width = unit(5, "pt")) 

# assign new title back to gt
gt$grobs[[which(gt$layout$name == "caption")]] <- new.title

grid.newpage()
grid.draw(gt)