Animated IRL Pirate Attacks In R

September 19, 2013

(This article was first published on » R, and kindly contributed to R-bloggers)

Avast me hearRties! (ok, enough of the pirate speak in a blog post)

It wouldn’t be TLAPD without out some modest code & idea pilfering from Mark Bulling & Simon Raper. While those mateys did a fine job hoisting up some R code (your really didn’t think I’d stop with the pirate speak, did you?) for their example, I took it one step furrrrther to build an animation of cumulative, yearly IRL pirate attacks from 1978 to the present. I found it a bit interesting to see how the hotspots shifted over time. Click on the graphic for the largeR version or I’ll make ye walk the plank!!.


# piRate the data from the militaRy
download.file("", destfile="")
# extRact the data fRame we need fRom the shape file
pirates.df <-"ASAM 19 SEP 13")) # you may need to use a diffeRent name depending on d/l date
# get the woRld map data
world <- map_data("world")
world <- subset(world, region != "Antarctica") # inteRcouRse AntaRctica
# yeaRs we want to loop thoRugh
ends <- 1979:2013
# loop thRough, extRact data, build plot, save plot: BOOM
for (end in ends) {
  png(filename=sprintf("arrr-%d.png",end),width=500,height=250,bg="white") # change to 1000x500 or laRgeR
  dec.df <- pirates.df[pirates.df$DateOfOcc > "1970-01-01" & pirates.df$DateOfOcc < as.Date(sprintf("%s-12-31",end)),] 
  rng <- range(dec.df$DateOfOcc)
  p <- ggplot() 
  p <- p + geom_polygon(data=world, aes(x=long, y=lat, group=group), fill="gray40", colour="white")
  p <- p + stat_summary_hex(fun="length", data=dec.df, aes(x=coords.x1, y=coords.x2, z=coords.x2), alpha=0.8)
  p <- p + scale_fill_gradient(low="white", high="red", "Pirate Attacks recorded")
  p <- p + theme_bw() + labs(x="",y="", title=sprintf("Pirate Attacks From %s to %s",rng[1],rng[2]))
  p <- p + theme(panel.background = element_rect(fill='#A6BDDB', colour='white'))
# requires imagemagick
system("convert -delay 45 -loop 0 arrr*g arrr500.gif")

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