Use image instead of labels in ggplot2 legend
Question
I have a plot in ggplot2 with, say, 2 lines, and in the legend I have "Sharks" and "Tigers". Is there a way I could have shark/tiger images appear in the legend instead of that text?
Solution
You're much better off using ggsave
to save the figure as a eps
or svg
, then opening it in Illustrator (or open source equivalent) and replacing the legend with the images. If you're really dead set on doing it all in R, you can use annotation_raster
in the current ggplot2
and add in some text next to it using geom_text
. Here is a rough attempt:
set.seed(10)
library(ggplot2)
library(RCurl)
library(png)
df <- data.frame(animal = sample(c("sharks", "tigers"),20, rep=T), time=1:20,
scariness = rnorm(20)*-20)
shark <- readPNG(getURLContent("http://i.imgur.com/EOc2V.png"))
tiger <- readPNG(getURLContent("http://i.imgur.com/zjIh5.png"))
ggplot(df, aes(time, scariness, group = animal, color = animal)) +
geom_line(show_guide = FALSE) +
annotation_raster(tiger, xmin = nrow(df)-1, xmax = nrow(df),
ymin = max(df$scariness)-(.05*max(df$scariness)),
ymax = max(df$scariness), interpolate = T) +
annotation_raster(shark, xmin = nrow(df)-1, xmax = nrow(df),
ymin = max(df$scariness)-(.1*max(df$scariness)),
ymax = max(df$scariness)-(.05*max(df$scariness)), interpolate = T)
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