Articles - R

Create an animated .gif image with R and ImageMagick

|    |   13981  |  Comment (1)  |  R


The purpose of this tutorial is to show you the steps to create an animated gif image with R and ImageMagick. You must first install ImageMagick.




It is also possible to create animated .gif images using only R, through write.gif() in caTools package.



The R code described in this tutotriel were tested on Mac OS X 10.6.8 with R 2.13





Example 1: Create a countdown




R code




The countdown is from 10 to 1. We will create it in 4 steps.

1 - Creating a clean working directory called 'examples'.
2 - Creating .png images, each containing a number (10 to 1).
3 - Creating a single image. Gif using ImageMagick
4 - delete png files that are no longer needed

The corresponding R code is shown below:

Code R :
 
#crearing working directory
dir.create("examples")
setwd("examples") 
 
#Creating countdown .png files from 10 to "GO!"
png(file="example%02d.png", width=200, height=200)
  for (i in c(10:1, "G0!")){
    plot.new()
    text(.5, .5, i, cex = 6)
  }
dev.off()
 
# Converting .png files in one .gif image using ImageMagick
system("/opt/local/bin/convert -delay 80 *.png example_1.gif")
# Remove .png files from working directory
file.remove(list.files(pattern=".png"))
 




1 - The system() function executs the conversion command as in a terminal. I use the absolute path to the convert command. In my case it is: /opt/ local/bin/convert. In some cases the command system("convert -delay 80 *. Example_1.gif png") works.

2 - the flag -delay is the time between two images (the speed of the animation).
3-The part "%02d" in the filename increment automatically the .png file names



Result




The result is :





Example 2: Creating a 3D animated graphic



We will create a 3D surface plot to visualize a linear model using lattice package. 3D graphics can be created also with rgl package.




R code




Code R :
 
library(lattice)
b0 <- 10
b1 <- .5
b2 <- .3
g <- expand.grid(x = 1:20, y = 1:20)
g$z <- b0 + b1*g$x + b2*g$y
 
png(file="example%03d.png", width=300, heigh=300)
  for (i in seq(0, 350 , 10)){
    print(wireframe(z ~ x * y, data = g,
              screen = list(z = i, x = -60)))
  }
dev.off()
 
# converting .png file in .gif using ImageMagick
system("/opt/local/bin/convert -delay 40 *.png example_2_reduced.gif")
 
# Remove .png file
file.remove(list.files(pattern=".png"))
 
 




Result







Source :
http://ryouready.wordpress.com/2010/11/21/animate-gif-images-in-r-imagemagick/