ggplot2 - photo alignment with graph in r

Question

First I thought I need to it manually in powerpoint, then I thought may be try with R, if there is a solution. Here is my example data:

set.seed(123)
myd<- expand.grid('cat' = LETTERS[1:5], 'cond'= c(F,T), 'phase' = c("Interphase", "Prophase", "Metaphase", "Anaphase", "Telophase"))
myd$value <- floor((rnorm(nrow(myd)))*100)
myd$value[myd$value < 0] <- 0

require(ggplot2)
ggplot() +
  geom_bar(data=myd, aes(y = value, x = phase, fill = cat), stat="identity",position='dodge') +
  theme_bw()

Here is what output should look like:

The jpeg image can be randomly generated (to demo examples) or example figures at the links:

Interphase prophase , metaphase, anaphase , telophase

Edit:

Suggestion @bapste

Answer 1

You can create a custom element function for axis.text.x, but it's quite fiddly and convoluted. Similar requests have been made in the past, it would be nice to have a clean solution for this and other custom changes (strip labels, axes, etc.) Feature request, anyone?

library(jpeg)
img <- lapply(list.files(pattern="jpg"), readJPEG )
names(img) <- c("Anaphase", "Interphase", "Metaphase", "Prophase", "Telophase")

require(ggplot2)
require(grid)

# user-level interface to the element grob
my_axis = function(img) {
    structure(
      list(img=img),
      class = c("element_custom","element_blank", "element") # inheritance test workaround
    )
  }
# returns a gTree with two children: the text label, and a rasterGrob below
element_grob.element_custom <- function(element, x,...)  {
  stopifnot(length(x) == length(element$img))
  tag <- names(element$img)
  # add vertical padding to leave space
  g1 <- textGrob(paste0(tag, "




"), x=x,vjust=0.6)
  g2 <- mapply(rasterGrob, x=x, image = element$img[tag], 
               MoreArgs = list(vjust=0.7,interpolate=FALSE,
                               height=unit(5,"lines")),
               SIMPLIFY = FALSE)

  gTree(children=do.call(gList,c(g2,list(g1))), cl = "custom_axis")
}
# gTrees don't know their size and ggplot would squash it, so give it room
grobHeight.custom_axis = heightDetails.custom_axis = function(x, ...)
  unit(6, "lines")

ggplot(myd) +
  geom_bar(aes(y = value, x = phase, fill = cat), stat="identity", position='dodge') +
  theme_bw() +
  theme(axis.text.x = my_axis(img),
          axis.title.x = element_blank())

ggsave("test.png",p,width=10,height=8)