Corner Labels in ggplot2

Question

I\'m interested in trying to create simple corner labels for a multipanel figure I am preparing in ggplot. This is similar to this previously asked question, but the answers

Answer 1

Here's a solution using a custom labeller function. This doesn't invovle any manipulations to the data. Currently it only works with 1-dimensional facets (facet_wrap). I'm still working on how to increment along a 2-D grid...

1. Define the labeller function

   make_labelstring <- function(mypanels) {
     mylabels <- sapply(mypanels, 
                        function(x) {LETTERS[which(mypanels == x)]})
   
     return(mylabels)
   }
   
   label_panels <- ggplot2::as_labeller(make_labelstring)
   

2. Pass label_panels as the labeller to facet_wrap

   library(ggplot2)
   data("diamonds")
   
   # create a faceted plot
   ggplot(data = diamonds, aes(x = depth, y = price)) +
     geom_point() +
     facet_wrap(~cut, labeller = label_panels) +
     theme(strip.text = element_text(hjust = -0),
           strip.background = element_blank())