Package ''animation'' before 0.2-1

Prior to animation (⇐ 0.2-0) the way to control animation parameters is quite different to later releases (> 0.2-0). If you are still using the old versions, please read the usage and animation method below.

Running animations either inside R (in graphical devices) or outside R (in HTML pages) are OK, as an argument saveANI (actually in the argument control using the function ani.control()) to decide whether to save PNG files.

By ani.start(), specifying saveANI = TRUE, and ani.stop(), you can generate an HTML page containing the animation; or if saveANI = FALSE, the animations will be shown inside R graphical devices.

For further information, please check the help pages or the vignette.

How to generate an animation sequence and save it?

The animation method behind the package is quite naive and intuitive; here is an example showing how it works:

for (i in 1:360) {
    plot(1, ann = F, type = "n", axes = F)
    text(1, 1, "Animation", srt = i, col = rainbow(360)[i], cex = 7 * 
        i/360)
    Sys.sleep(0.01)
} 

The above R code will produce an animation like this:

Almost all of the animation functions in the package just follow this kind of loop to produce a sequence of image frames.

Here is the pseudo code for the general schema used in the package:

ani.fun <- function(args.stat.method, control = ani.control(nmax = 100, 
    interval = 0.05, width, height, ...), ...) {
    control = checkargs(control, ...)
    (stat.calculation.for.preparation.here)
    i = 1
    while (i <= control$nmax) {
        (stat.calculation.for.animation)
        (plot.results.in.ith.step)
        if (control$saveANI) 
            savePNG(n = i, width = control$width, height = control$height)
        else Sys.sleep(control$interval)
        i = i + 1
    }
    (return.something)
} 

The animation in the HTML pages is actually driven by JS. For more details, please refer to the HTML animation examples and the animation plugin for Dokuwiki.

The package has also provided a wrapper to generate GIF animations together with ImageMagic. The method is even easier; we merely need to write some code which can produce a sequence of images, and the rest work will be done by the function saveMovie() in the package. See the example in the “Examples” section.

Currently we can directly use the functions in the package to produce animations, or we can also define animation functions for ourselves.

library(animation)
 
# inside R: windows graphics device
brownian.motion(n = 15, nmax = 150) 
 
# outside R: create an HTML animation page
ani.start()
brownian.motion(n = 15, nmax = 100, saveANI = TRUE, width = 500, height = 500) 
ani.stop() 

The following code has explained how to define animation functions for yourself (please read the general schema above first):

library(animation)
# define an animation function to show the jitter effect
jitter.ani <- function(control = ani.control(), ...) {
    control = checkargs(control, ...)
    x <- 1:100
    i <- 1
    while (i <= 30) {
        plot(x, jitter(x, amount = 5), ylim = c(1, 100), ylab = "jittered x", 
            panel.first = {
                grid()
                abline(0, 1, col = "darkgray")
            })
        if (control$saveANI) 
            savePNG(n = i, width = control$width, height = control$height)
        else Sys.sleep(control$interval)
        i <- i + 1
    }
}
ani.start()
jitter.ani(saveANI = TRUE, interval = 0.5)
ani.stop() 

Following the above example, we pass an expression to the function saveMovie() to create a similar animation:

library(animation)
saveMovie(for (i in 1:30) plot(x, jitter(x, amount = 5), 
    ylim = c(1, 100), ylab = "jittered x", panel.first = {
        grid()
        abline(0, 1, col = "darkgray")
    }), interval = 0.5, outdir = getwd()) 
# the GIF animation 'movie.gif' will be created in the directory getwd()

Or this code will be more clear:

library(animation)
ani.expr <- expression(for (i in 1:30) plot(x, jitter(x, 
    amount = 5), ylim = c(1, 100), ylab = "jittered x", panel.first = {
    grid()
    abline(0, 1, col = "darkgray")
}))
saveMovie(ani.expr, interval = 0.5, outdir = getwd()) 

Here is the old vignette. If anybody wants to continue my work, please download the LaTeX source (Sweave).