How do I overlay an image on to a ggplot?

Question

I\'d like to read an image from the web. e.g.

http://api.altmetric.com/donut/502878_64x64.png

and insert it into the top right of a ggplot

Answer 1

You are looking for annotation_raster and readPNG

mypngfile <- download.file('http://api.altmetric.com/donut/502878_64x64.png', destfile = 'mypng.png', mode = 'wb')
library(png)
mypng <- readPNG('mypng.png')


p <- qplot(mpg, wt, data = mtcars) + theme_bw()
p + annotation_raster(mypng, ymin = 4.5,ymax= 5,xmin = 30,xmax = 35) + 
    geom_point()

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