Wednesday, January 2, 2013

Producing animated GIFs and Videos


It took me a while to figure out how to use the animation package on my Windows OS. In making an animated GIF, the problem seems to have been quite simple in the end (and I should have been more patient in reading the instructions!) - Following installation of the program ImageMagick, one has to define where the program convert.exe is located using 'ani.options()'.

One is also able to make great videos:


video





To reproduce the example (requires 'spirographR' function):

###Required function
source("spirographR.R") #http://menugget.blogspot.de/2012/12/spirograph-with-r.html
 
###Required package
require(animation)
 
###Create spirograph
a.rad = 4
b.rad = -5
bc = 2
a.rev = 5
n.per.a.rev=180
coord <- spirographR(
 A.RADIUS=a.rad,
 B.RADIUS=b.rad,
 BC=bc,
 A.REV=a.rev,
 N.PER.A.REV=n.per.a.rev 
)
 
plot(coord, asp=1, t="l")
 
 
#######################
###Make animated GIF###
#######################
 
#Define path to convert.exe (http://www.imagemagick.org)
ani.options(
convert = shQuote('C:/Program Files (x86)/ImageMagick-6.8.1-Q16/convert.exe')
)
 
#Setup
STEPS <- seq(1, length(coord$x), , 100) #reduces the number of frames
SEQ <- seq(length(coord$x))
TAIL <- 150
 
COL1 <- heat.colors(TAIL)
PAL <- colorRampPalette(c("blue", "cyan", "white"))
COL2 <- PAL(TAIL)
LWD <- seq(0.1,10,,TAIL)
 
#Make GIF
saveGIF(
{
 par(mar=c(0,0,0,0), bg=1);
 for(i in round(STEPS)){
  #i=850
  plot(coord$x, coord$y, asp=1, t="n")
  STARTS1 <- (c(i:(i+TAIL-1)) %% length(coord$x)) + 1
  STOPS1 <- c(i:(i+TAIL-1)) %% length(coord$x) + 2
  segments(x0=coord$x[STARTS1], x1=coord$x[STOPS1], y0=coord$y[STARTS1], y1=coord$y[STOPS1], col=COL1, lwd=LWD)
 
  j <- i + TAIL*2
  STARTS2 <- (c(j:(j+TAIL-1)) %% length(coord$x)) + 1
  STOPS2 <- c(j:(j+TAIL-1)) %% length(coord$x) + 2
  segments(x0=coord$x[STARTS2], x1=coord$x[STOPS2], y0=coord$y[STARTS2], y1=coord$y[STOPS2], col=COL2, lwd=LWD)
 
 }
},
movie.name = "spirograph2.gif", 
interval = 0.02, 
ani.width = 300, 
ani.height = 300,
nmax=length(SEQ),
outdir = getwd()
)
 
 
################
###Make video###
################
 
#Setup
SEQ <- seq(1, length(coord$x), , 300)
COL <- rainbow(length(coord$x)-1)
LWD <- seq(1, 10, , length(coord$x)-1)
 
#Make video
saveVideo(
{
 par(mar=c(0,0,0,0), bg=1);
 for(i in seq(SEQ)[-1]){
  plot(coord$x, coord$y, asp=1, t="n")
  segments(x0=coord$x[seq(SEQ[i])[-(SEQ[i])]], x1=coord$x[seq(SEQ[i])[-1]], y0=coord$y[seq(SEQ[i])[-(SEQ[i])]], y1=coord$y[seq(SEQ[i])[-1]], col=COL[seq(SEQ[i])], lwd=LWD[seq(SEQ[i])])
 }
},
video.name = "spirograph.mp4", 
interval = 0.05, 
ani.width = 300, 
ani.height = 300,
nmax=length(SEQ),
outdir = getwd()
)
Created by Pretty R at inside-R.org




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