dempyrenees.asc データの紹介

require(ggplot2)
require(insol)
require(data.table) 

zipfile=tempfile()
download.file("http://www.meteoexploration.com/R/insol/data/dempyrenees.asc.zip", zipfile)
header= data.table( read.table(unz(zipfile, 'dempyrenees.asc'), nrows=6, as.is=TRUE) )
dem = data.table( read.table(unz(zipfile, 'dempyrenees.asc'), skip=6, as.is=TRUE) ) 
dem=as.matrix(dem)
unlink(zipfile)


plotdem <- function(DEM, c) { 
  x <- rep(1:nrow(DEM), ncol(DEM))      # 1 2 3 1 2 3 1 2 3 1 2 3
  y <- rep(1:ncol(DEM), each=nrow(DEM)) # 1 1 1 1 2 2 2 2 3 3 3 3

  T <- data.table(x=x, y=y, val=as.numeric(DEM))
  ggplot(T, aes(x=x, y=y, fill=val)) + geom_tile() + scale_fill_gradientn("frequency", colours = c)
}

plotdem(dem, terrain.colors(20)) 
contour(dem)