Workaround to plot labels at precise points using plotROC

plotROC-custom-labels.R

library(plotROC)
D <- rbinom(100, 1, .4)
fkd <- data.frame(D = D, Y = rnorm(100, mean = D, sd = .5))

p1 <- ggplot(fkd, aes(d = D, m = Y)) + geom_roc(n.cuts = 0)
dat <- ggplot_build(p1)$data[[1]]

mycut.i <- c(10, 50, 90) # find the indices of the labels you want to plot in dat above

p1 + geom_point(data = dat[mycut.i, ], 
                aes(d = NULL, m = NULL, x = x, y = y)) + 
  geom_text(data = dat[mycut.i, ], 
            aes(d = NULL, m = NULL, x = x - .03, y = y + .03, label = round(cutoffs, 1)))

p1 + geom_point(data = dat[mycut.i, ], 
                aes(d = NULL, m = NULL, x = x, y = y)) + 
  geom_label(data = dat[mycut.i, ], 
            aes(d = NULL, m = NULL, x = x - .03, y = y + .03, label = round(cutoffs, 1)))