Site icon R-bloggers

Custom axis transformations in ggplot2

[This article was first published on NumberTheory » R stuff, 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.

To apply a data transformation on an axis in a ggplot, you can use coordinate transformations. For more detail see the ggplot2 documentation. A number of coordinate transformations is available, including log10 and sqrt. However, if you want to perform a custom transformation this is not trivial. Say the transformation involves x = 1/x. To get this transformation available you can define the following function (see ?trans_new for more details):

require(scales) # trans_new() is in the scales library
one_over_trans = function() trans_new("one_over", function(x) 1/x, function(x) 1/x)

from now one you can use one_over as a coordinate transform. Note that the name convention is nameoftrans_trans. Example code:

qplot(carat, price, data=diamonds) + coord_trans(x = "log10", y = "one_over")

To leave a comment for the author, please follow the link and comment on their blog: NumberTheory » R stuff.

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.