plot emoji/custom image in axis labels in R

Question

I'm trying to plot Emojis and custom images in R as labels of X axis. I've read similar threads and questions, but I don't want to use emojifont in R, and instead use my own images as label (.png) and there's around 270 of these custom emojis.

I followed this article and managed to show emojis at top of bars, but I want the emojis as labels. similar to this image.

The only solution that came to my mind was changing value of density in mapply (df.plot$dens) to 1, in this code:

...
mapply(function(x, y, i) {
          annotation_custom(g[[i]], xmin = x-0.5*df.plot$xsize[i], xmax = x+0.5*df.plot$xsize[i], 
                            ymin = y-0.5*df.plot$ysize[i], ymax = y+0.5*df.plot$ysize[i])},
          df.plot$rank, df.plot$dens, seq_len(nrow(df.plot)))
...

Therefore, the code is :

g1 <- ggplot(data = df.plot, aes(x = rank, y = dens)) +
  geom_bar(stat = 'identity', fill = 'dodgerblue4') +
  xlab(xlab) + ylab(ylab) +
  mapply(function(x, y, i) {
    annotation_custom(g[[i]], xmin = x-0.5*df.plot$xsize[i], xmax = x+0.5*df.plot$xsize[i], 
                      ymin = y-0.5*df.plot$ysize[i], ymax = y+0.5*df.plot$ysize[i])},
    df.plot$rank, 1, seq_len(nrow(df.plot))) +
  scale_x_continuous(expand = c(0, 0), breaks = seq(1, nrow(df.plot), 1), labels = seq(1, nrow(df.plot), 1)) +
  scale_y_continuous(expand = c(0, 0), limits = c(0, 1.10 * max(df.plot$dens))) +
  theme(panel.grid.minor.y = element_blank(),
        axis.title.x = element_text(size = 10), axis.title.y = element_text(size = 14), 
        axis.text.x  = element_text(size = 8, colour = 'black'), axis.text.y  = element_text(size = 8, colour = 'black'));
g1;

and the results is :

Is there anyway to use .png as labels instead of text or emojifont, in R?

As for data, I've :

 df.plot

   description                         n  dens  rank xsize ysize
   <fct>                           <int> <dbl> <dbl> <dbl> <dbl>
 1 crying face                      1207   1.5     8  9.62  7.22
 2 double exclamation mark          1326   1.6     7  9.62  7.22
 3 face with tears of joy          39122  48.1     1  9.62  7.22
 4 grinning face                     871   1.1    10  9.62  7.22
 5 grinning face with smiling eyes  1872   2.3     4  9.62  7.22
 6 hugging face                     1401   1.7     6  9.62  7.22
 7 hundred points                   2998   3.7     3  9.62  7.22
 8 loudly crying face              13375  16.4     2  9.62  7.22
 9 party popper                     1522   1.9     5  9.62  7.22
10 tired face                        974   1.2     9  9.62  7.22

and g is referring to images:

imgs <- lapply(paste0(df.plot$description, '.png'), png::readPNG); 
g <- lapply(imgs, grid::rasterGrob);

Answer 1

I found the solution. The answer to similar question is given in photo alignment with graph in r and here.

We need to create a function

my_axis = function(img) {
  structure(
    list(img=img),
    class = c("element_custom","element_blank", "element") # inheritance test workaround
  )
}

To make it look better I suggest to use rot=45 to rotate the labels

   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, "\n\n\n\n\n"), x=x, vjust=0.6,rot = 45)
  g2 <- mapply(rasterGrob, x=x, image=element$img[tag], 
               MoreArgs=list(vjust=0.6, interpolate=FALSE,
                             height=unit(3,"lines")),
               SIMPLIFY=FALSE)
  gTree(children=do.call(gList, c(g2, list(g1))), cl="custom_axis")
}

and then call it:

gg <- gg + theme(axis.text.x  = my_axis(pics),
                 axis.text.y  = element_text(size=14),
                 axis.title.x = element_blank())

The output :