CODEWITHSUNDEEP
rggplot2rasterpurrr
Adam Kemberling
Adam Kemberling

Reputation: 311

Way to overlay an image on each ggplot object in a list using grid.raster?

I have a list of ggplot objects that I want to place a logo onto in the same relative position without having to specify new x,y coordinates for when the axes are different.

The application of grid::grid.raster() is exactly how I want it to perform, but I can't sort out how to apply it to objects in my list and not my open graphics device.

annotate_custom() & annotate_raster() (as far as I can tell) will require me to set positioning according to the data for each plot which is not ideal.

library(magick)
library(ggplot2)
library(grid)
library(purrr)

stock_image <- image_read_svg('http://jeroen.github.io/images/tiger.svg', width = 400)
print(stock_image)

#make a ggplot object for example
any_ggplot <- qplot(mtcars$hp, mtcars$mpg)

#make a list of them
plot_list <- rep(list(any_ggplot), 4)

#the goal is to put that image on all of them, and save the new plots in a list.

# I can do it once with grid.raster,
# And this is the preferred method because the scaling and position is consistent 
# even if the axes change
grid::grid.raster(stock_image, x = 0.5, y = 0.5, just = c('left', 'bottom'), width = unit(1.5, 'inches'))


# But I can't do it to the list
new_plot_list <- purrr::map(plot_list, function(x) {

  x
  grid::grid.raster(stock_image, x = 0.5, y = 0.5, just = c('left', 'bottom'), width = unit(1.5, 'inches'))


})

#Help?

Ideally each plot would now have that image overlaid on it. But, currently what is happening is the image is overlaid on the open plot and no list is returned.

I think I need to isolate the graphics device for each one, but I'm not sure, and may not.

Upvotes: 3

Views: 925

Answers (2)

astrofunkswag
astrofunkswag

Reputation: 2698

Utilizing this post

img <- rasterGrob(stock_image, interpolate=TRUE, x = .5, y = .5, just = c('left', 'bottom'), width = unit(1.5, 'inches'))

any_ggplot +
  annotation_custom(img, xmin=-Inf, xmax=Inf, ymin=-Inf, ymax=Inf)


new_plot_list <- purrr::map(plot_list, function(x) {
  x +
    annotation_custom(img, xmin=-Inf, xmax=Inf, ymin=-Inf, ymax=Inf)
})

Upvotes: 0

Marco Sandri
Marco Sandri

Reputation: 24262

Here is a possibile solution:

library(ggplot2)
library(purrr)
library(cowplot)
library(gridExtra)
library(magick)

stock_image <- image_read_svg('http://jeroen.github.io/images/tiger.svg', width = 400)

# Make 4 ggplot objects for example
any_ggplot1 <- qplot(mtcars$hp, mtcars$mpg)
any_ggplot2 <- qplot(mtcars$drat, mtcars$mpg)
any_ggplot3 <- qplot(mtcars$wt, mtcars$cyl)
any_ggplot4 <- qplot(mtcars$disp, mtcars$cyl)

# Make a list of them
plot_list <- list(any_ggplot1, any_ggplot2, any_ggplot3, any_ggplot4)

new_plot_list <- purrr::map(plot_list, function(x) {
    ggdraw() +
      draw_image(stock_image, x = 0.25, y = 0.25, scale=0.25) +
      draw_plot(x)
})

grid.arrange(grobs=new_plot_list)

enter image description here

Upvotes: 3

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