2 min read

Making GIFs in R

2021-02-20

I recently tried out the gganimate R package and made some simple dynamic plots. Today I want to try out two other packages; gifski and magick, to see how easy it is to export some simple GIFs. It looks like magick can do a lot of image processing tasks, while gifski is pretty focused on the one task: images > GIF.

Load some R packages

library(tidyverse)
library(gifski)
library(magick)

Static sine wave

We will create a static plot first:

ggplot(data = tibble(x=seq(0,10,0.1), y=sin(seq(0,10,0.1))),
       aes(x=x, y=y)) +
  geom_point() +
  ggtitle(" A Static Sine Wave")

gifski

Now we will try create a dynamic version with gifksi:

plot_sine <- function(i) {
  p <- ggplot(data = data.frame(x=i,y=sin(i)), aes(x=x, y=y)) + 
    geom_point() + 
    ylim(c(-1,1)) +
    xlim(c(0,10)) +
    ggtitle("A Dynamic Sine Wave")
  print(p)
  }

save_gif(expr = pwalk(list(seq(0,10,0.1)), plot_sine),
         gif_file = "gifski_sine_wave.gif",
         width = 72*6, height = 72*3, res=72,
         delay = 0.1, loop = TRUE, progress = FALSE)

magick

Now we’ll try the same with 🎩🐇:

# Make a directory to save png images in
dir.create("sine_wave_images")

# Create images
walk(1:101, function(i) ggsave(filename = str_glue('sine_wave_images/{str_pad(i,3,"left","0")}.png'),
                              plot = plot_sine(seq(0,10,0.1)[i]),
                              width = 6,height = 3, units = "in", dpi=72))

# Read in images, stitch them together, animate and write out
lapply(list.files("sine_wave_images/", full.names = TRUE),
       image_read) %>% 
  image_join() %>%
  image_animate(fps = 10) %>%
  image_write(path = "magick_sine_wave.gif")

File sizes

Check the size of each GIF file: utils:::format.object_size(file.size("gifski_sine_wave.gif"), units = "auto")

139.5 Kb

utils:::format.object_size(file.size("magick_sine_wave.gif"), units = "auto")

1.6 Mb

The magick gif is ~10 times larger … I’m not sure why. gifski has another function save_gif. Let’s try use that function to create a GIF using the same images we used with magick, then check the file size.

gifski::save_gif()

Using the same png files:

gifski(png_files = list.files("sine_wave_images/", full.names = TRUE),
       gif_file = "gifski_sine_wave2.gif", 
       width = 72*6, height = 72*3,
       delay = 0.1, loop = TRUE, progress = TRUE)

# Individual images no longer spark joy
unlink("sine_wave_images/", recursive = TRUE)

Check the size of the new GIF utils:::format.object_size(file.size("gifski_sine_wave2.gif"), units = "auto")

139.5 Kb

It’s the same size 🤷. There’s probably some magick options we could tweak to reduce the file size, but since this was just for fun I’ll leave it there for now.