pit.R

library(cowplot)
n <- 1e4
X <- rlogis(n)
Y <- plogis(X)
plot_dens <- function(data, ...) {
  qplot(
    data,
    geom = "histogram",
    alpha = I(1 / 2), 
    ...
  ) + xlab("")
}
pl <- plot_dens(X) + ggtitle("Logistic Distribution")
pu <- plot_dens(Y) + ggtitle("Uniform from Logistic")
plot_grid(pl, pu)