justifying tables with annotation_custom

just-table.R

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

justify <- function(x, hjust="center", vjust="center", draw=FALSE){
  w <- sum(x$widths)
  h <- sum(x$heights)
  xj <- switch(hjust,
               center = 0.5,
               left = 0.5*w,
               right=unit(1,"npc") - 0.5*w)
  yj <- switch(vjust,
               center = 0.5,
               bottom = 0.5*h,
               top=unit(1,"npc") - 0.5*h)
  x$vp <- viewport(x=xj, y=yj)
  if(draw) grid.draw(x)
  return(x)
}

p <- ggplot(mpg, aes(displ, cty)) + geom_point()

tg <- tableGrob(mpg[1:3,2:3])

p + annotation_custom(grobTree(justify(tg, "right", "top")))


p2 <- p + facet_grid(. ~ cyl)
ltg <- plyr::dlply(mpg, "cyl", function(d) grobTree(justify(tableGrob(d[1:3,3:5]), "right", "top")))
dummy <- cbind(attr(ltg,"split_labels"), I(ltg))

p2 + geom_custom(data = dummy, aes(0,0,data=ltg), grob_fun = identity)