# Insert animations into an HTML page

### Yihui Xie & Lijia Yu / 2017-04-04

This function first records all the plots in the R expression as bitmap images, then inserts them into an HTML page and finally creates the animation using the SciAnimator library.

It mainly uses the SciAnimator library, which is based on jQuery. It has a neat interface (both technically and visually) and is much easier to use or extend. Moreover, this function allows multiple animations in a single HTML page – just use the same HTML filename.

Optionally the source code and some session information can be added below the animations for the sake of reproducibility (specified by the option ani.options('verbose') – if TRUE, the description, loaded packages, the code to produce the animation, as well as a part of sessionInfo() will be written in the bottom of the animation; the R code will be highlighted using the SyntaxHighlighter library for better reading experience).

library(animation)
## A quick and dirty demo
des = c("This is a silly example.\n\n", "You can describe it in more detail.",
"For example, bla bla...")
saveHTML({
par(mar = c(4, 4, 0.5, 0.5))
for (i in 1:20) {
plot(runif(20), ylim = c(0, 1))
ani.pause()
}
}, img.name = "unif_plot", imgdir = "unif_dir", htmlfile = "random.html",
autobrowse = FALSE, title = "Demo of 20 uniform random numbers",
description = des)

## we can merge another animation into the former page as long
## as 'htmlfile' is the same; this time I don't want the
## animation to autoplay, and will use text labels for the
## buttons (instead of UTF-8 symbols)
des = c("When you write a long long long long description, R will try to wrap the",
"words automatically.", "Oh, really?!")
saveHTML({
par(mar = c(4, 4, 0.5, 0.5))
ani.options(interval = 0.5)
for (i in 1:10) {
plot(rnorm(50), ylim = c(-3, 3))
ani.pause()
}
}, img.name = "norm_plot", single.opts = "utf8: false", autoplay = FALSE,
interval = 0.5, imgdir = "norm_dir", htmlfile = "random.html",
ani.height = 400, ani.width = 600, title = "Demo of 50 Normal random numbers",
description = des)

## use the function brownian.motion() in this package; this
## page is created in 'index.html' under the current working
## directory
des = c("Random walk of 10 points on the 2D plane:", "for each point (x, y),",
"x = x + rnorm(1) and y = y + rnorm(1).")
saveHTML({
par(mar = c(3, 3, 1, 0.5), mgp = c(2, 0.5, 0), tcl = -0.3,
cex.axis = 0.8, cex.lab = 0.8, cex.main = 1)
ani.options(interval = 0.05, nmax = 150)
brownian.motion(pch = 21, cex = 5, col = "red", bg = "yellow")
}, img.name = "brownian_motion_a", htmlfile = "index.html", description = des)

## remove the 'navigator' (progress bar)
saveHTML({
par(mar = c(3, 3, 1, 0.5), mgp = c(2, 0.5, 0), tcl = -0.3,
cex.axis = 0.8, cex.lab = 0.8, cex.main = 1)
ani.options(interval = 0.05, nmax = 150)
brownian.motion(pch = 21, cex = 5, col = "red", bg = "yellow")
}, img.name = "brownian_motion_b", htmlfile = "index.html", navigator = FALSE,
description = c("Random walk of 10 points on the 2D plane",
"(without the navigation panel)"))

## use Rweb to create animations
if (interactive()) browseURL(system.file("misc", "Rweb", "demo.html",
package = "animation"))