setting ggplot2 background with ggbackground

April 18, 2018
By

[This article was first published on R on Guangchuang YU, and kindly contributed to R-bloggers]. (You can report issue about the content on this page here)
Want to share your content on R-bloggers? click here if you have a blog, or here if you don't.

ggimage 0.1.4 is available on CRAN.

This release introduces a new function called ggbackground for setting image background as ggplot canvas.

require(ggplot2)
p <- ggplot(iris) + aes(x = Sepal.Length, y = Sepal.Width, color=Species) + 
    geom_point(size=5) + theme_classic()

Suppose we have the above ggplot object, p, the only thing we need to do is passing the p with an image file name (local or remote) to ggbackground, as demonstrated below:

require(ggimage) 
img = "https://assets.bakker.com/ProductPics/560x676/10028-00-BAKI_20170109094316.jpg"
ggbackground(p, img)

This image file is too colorful and it is hard to see the patterns of the data points. We can manipulate the image using the functions provided by magick package. For example, the following function emulate a classic high-pass filter from photoshop:

require(magick)
ggbackground(p, img, 
    image_fun = function(x) image_negate(image_convolve(x, 'DoG:0,0,2')))

Here are examples of setting transparency and color:

img = "http://phylopic.org/assets/images/submissions/bf5fe2c5-1247-4ed9-93e2-d5af255ec462.512.png"
p1 = ggbackground(p, img) + ggtitle("ggbackground(p, img)")
p2 = ggbackground(p, img, alpha=.3) + ggtitle("ggbackground(p, img, alpha=.3)")
p3 = ggbackground(p, img, alpha=.3, color="steelblue") + ggtitle('ggbackground(p, img, alpha=.3, color="steelblue")')
cowplot::plot_grid(p1, p2, p3, ncol=3)

To leave a comment for the author, please follow the link and comment on their blog: R on Guangchuang YU.

R-bloggers.com offers daily e-mail updates about R news and tutorials about learning R and many other topics. Click here if you're looking to post or find an R/data-science job.
Want to share your content on R-bloggers? click here if you have a blog, or here if you don't.



If you got this far, why not subscribe for updates from the site? Choose your flavor: e-mail, twitter, RSS, or facebook...

Comments are closed.

Search R-bloggers

Sponsors

Never miss an update!
Subscribe to R-bloggers to receive
e-mails with the latest R posts.
(You will not see this message again.)

Click here to close (This popup will not appear again)