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

I had the same problem and came up with the following solution, which is a bit different:

loading r packages

library(ggplot2)
library(grid)
library(gridExtra)

example data

a <- 1:20
b <- sample(a, 20)
c <- sample(b, 20)
d <- sample(c, 20)

create a data frame

mydata   <- data.frame(a, b, c, d)

create example plots

myplot1  <- ggplot(mydata, aes(x=a, y=b)) + geom_point()
myplot2  <- ggplot(mydata, aes(x=b, y=c)) + geom_point()
myplot3  <- ggplot(mydata, aes(x=c, y=d)) + geom_point()
myplot4  <- ggplot(mydata, aes(x=d, y=a)) + geom_point()

set corner labels

myplot1 <- arrangeGrob(myplot1, top = textGrob("A", x = unit(0, "npc")
         , y   = unit(1, "npc"), just=c("left","top"),
         gp=gpar(col="black", fontsize=18, fontfamily="Times Roman")))

myplot2 <- arrangeGrob(myplot2, top = textGrob("B", x = unit(0, "npc")
         , y = unit(1, "npc"), just=c("left","top"),
         gp=gpar(col="black", fontsize=18, fontfamily="Times Roman")))

myplot3 <- arrangeGrob(myplot3, top = textGrob("C", x = unit(0, "npc")
        , y  = unit(1, "npc"), just=c("left","top"),
        gp=gpar(col="black", fontsize=18, fontfamily="Times Roman")))

myplot4 <- arrangeGrob(myplot4, top = textGrob("D", x = unit(0, "npc")
        , y = unit(1, "npc"), just=c("left","top"),
        gp=gpar(col="black",    fontsize=18, fontfamily="Times Roman")))

plotting all plots on one page

grid.arrange(myplot1, myplot2, myplot3, myplot4, ncol = 2)