Highlighting selected values in busy plots with gghighlight

Bioinformatics datasets often comprise measurements of many items. The genomes we analyze have thousands of genes, but usually, we’re only interested in the few that respond to particular changes in the experiment we have designed. So, it’s of great use to be able to highlight those few in our plots. In this recipe, we’ll look at the gghighlight package, which can make that very easy.

Getting ready

We’ll need the gghighlight, ggplot2, and rbioinfcookbook packages for the main functions. We’ll also use dplyr briefly. The datasets for these are fission yeast wt versus mutant gene expression data and an Arabidopsis treatment timecourse. The columns in the data are for the log 2 ratio of gene expression in mutant versus wt and the p-value from a statistical test.

How to do it…

We can highlight selected values in a plot such as a gene expression plot using the following steps...