ggplot: place image in corner of panel

Question

I'm trying to find a way to insert an image into the corner of a ggplot panel, without specifying the coordinates manually each time.

In this instance, I'm attempting to place a graphic in the top right.

library(magick)
library(ggplot2)
library(datasets)

homer <- magick::image_read("http://icons.iconarchive.com/icons/jonathan-rey/simpsons/128/Homer-Simpson-04-Happy-icon.png")


g <- ggplot(mpg, aes(class)) +
  geom_bar() +
  labs(
    title = "Count of Auto by Class",
    subtitle = "Text to Create More Space")

g + annotation_custom(rasterGrob(homer, interpolate = TRUE),
                      xmax = Inf, ymax = Inf) +
  coord_cartesian(clip = "off")

I have found some examples that come close to solving this:

Inserting an image to ggplot outside the chart area

Corner Labels in ggplot2

But neither quite get there. Specifying the exact location at which to place the image seems to require quite a bit of trial-and-error on each plot created, especially when x is categorical.

I would also like to maintain the size of my original image; the code I've used above seems to stretch it across the plot.

Thanks in advance...much appreciated.

user10120412 user10120412 · Accepted Answer · 2018-07-23T05:31:37

try this

library(grid)
a <- rasterGrob(homer, interpolate = TRUE, 
                width=unit(1,'cm'),
           x = unit(1,"npc"), y = unit(1,"npc"),
           hjust = 1, vjust=1)

g + annotation_custom(grob = a)

ggplot: place image in corner of panel

1 Answers