Miscellaneous functions in package animation

Some of these functions are occasionally used in my daily life, and some are the implementations of my quick ideas when I see something interesting (like the visual illusions).

The function tidy.source() is defined as:

 > tidy.source
function(source = "clipboard", keep.comment = TRUE\, 
    keep.blank.line = FALSE\, begin.comment, end.comment, ...) {
    tidy.block = function(block.text) {
        exprs = parse(text = block.text)
        n = length(exprs)
        res = character(n)
        for (i in 1:n) {
            dep = paste(deparse(exprs[i]), collapse = "\n")
            res[i] = substring(dep, 12, nchar(dep) - 1)
        }
        return(res)
    }
    text.lines = readLines(source, warn = FALSE\)
    if (keep.comment) {
        identifier = function() paste(sample(LETTERS), collapse = "")
        if (missing(begin.comment)) 
            begin.comment = identifier()
        if (missing(end.comment)) 
            end.comment = identifier()
        text.lines = gsub("^[[:space:]]+|[[:space:]]+$", "", 
            text.lines)
        while (length(grep(sprintf("%s|%s", begin.comment, end.comment), 
            text.lines))) {
            begin.comment = identifier()
            end.comment = identifier()
        }
        head.comment = substring(text.lines, 1, 1) == "#"
        if (any(head.comment)) {
            text.lines[head.comment] = gsub("\"", "'", text.lines[head.comment])
            text.lines[head.comment] = sprintf("%s=\"%s%s\"", 
                begin.comment, text.lines[head.comment], end.comment)
        }
        blank.line = text.lines == ""
        if (any(blank.line) & keep.blank.line) 
            text.lines[blank.line] = sprintf("%s=\"%s\"", begin.comment, 
                end.comment)
        text.tidy = tidy.block(text.lines)
        text.tidy = gsub(sprintf("%s = \"|%s\"", begin.comment, 
            end.comment), "", text.tidy)
    }
    else {
        text.tidy = tidy.block(text.lines)
    }
    cat(paste(text.tidy, collapse = "\n"), "\n", ...)
    invisible(text.tidy)
}

As you have seen, it's quite simple. When I write R code, I'd like to “tidy” them up, because I don't want to type the spaces (either those around operators or those for indents). You just have to copy your code to the clipboard, then tidy.source(), and the (more standard) code will be printed in the console. For example, this is the original code:

f = tempfile()
writeLines('
 # rotation of the word "Animation"
# in a loop; change the angle and color
# step by step
for (i in 1:360) {
# redraw the plot again and again
plot(1,ann=FALSE,type="n",axes=FALSE)
# rotate; use rainbow() colors
text(1,1,"Animation",srt=i,col=rainbow(360)[i],cex=7*i/360)
# pause for a while
Sys.sleep(0.01)}
', f)

And this is the “tidy” version:

 > tidy.source(f)
# rotation of the word 'Animation'
# in a loop; change the angle and color
# step by step
for (i in 1:360) {
   # redraw the plot again and again
   plot(1, ann = FALSE\, type = "n", axes = FALSE\)
   # rotate; use rainbow() colors
   text(1, 1, "Animation", srt = i, col = rainbow(360)[i], cex = 7 *
       i/360)
   # pause for a while
   Sys.sleep(0.01)
}

Perhaps visual illusions can inspire ideas in animations.

White dots? Black dots?

vi.grid.illusion()

Gray dots at the intersections?

vi.grid.illusion(type = "h", lwd = 22, nrow = 5, ncol = 5, 
    col = "white")

Green dots moving?

oopt = ani.options(ani.height = 480, ani.width = 480, outdir = getwd(), nmax = 1,
    interval = 0.05, title = "Visual Illusions: Lilac Chaser",
    description = "Stare at the center cross for a few (say 30) seconds
    to experience the phenomena of the illusion.")
ani.start()
par(pty = "s", mar = rep(1, 4))
vi.lilac.chaser()
ani.stop()
ani.options(oopt)

An RSS feed is essentially just an XML file, thus the creation is easy just with cat() to write some tags into a text file. The elments of an item in an RSS feed usually contains title, link, author, description, pubDate, guid, and category, etc, which are stored in the CSV data file.

write.rss(entry = "http://r.yihui.name/news/rss.csv")