# Functions for lab 4
# by Tom Minka
# R 1.7.1

#############################################################################
# Standard startup

if(!exists("zip.unpack")) {
  zip.unpack <- function(path,destdir) {
    cmd = paste("unzip -q",path,"-d",destdir)
    status = system(cmd)
    if(status > 0) stop(paste("unzip failed.  do you have",path,"?"))
    status
  }
}

install.local <- function(package,path="",destdir=NULL,chdir=T) {
  if(is.null(destdir)) destdir = tempdir()
  if(path == "") {
    if(exists("choose.files"))
      path = choose.files(caption=paste("Select",package,"zip file"),multi=F)
    else
      path = "mining.zip"
  }
  zip.unpack(path,destdir)
  #package = basename(path)
  #package = strsplit(package,"_")[[1]][1]
  library(package,lib.loc=destdir,character.only=T,warn=F)
  if(chdir) {
    olddir = getwd()
    newdir = dirname(path)
    setwd(newdir)
    # get the canonical version of newdir
    newdir = getwd()
    if(newdir != olddir) {
      cat("Working directory is now",newdir,"\n")
    }
  }
}
my.require <- function(package) {
  package = deparse(substitute(package))
  if(length(.find.package(package,quiet=T))>0) library(package,char=T)
  else install.local(package)
}

my.require(mining)

#############################################################################

rgb2indexed <- function(img) {
  col <- rgb(img[,1],img[,2],img[,3])
  unique.col <- unique(col)
  ind <- match(col,unique.col)
  attr(ind,"col") <- unique.col
  ind
}
plot.image <- function(img,col) {
  if(missing(col)) {
    col <- attr(img,"col")
    if(is.null(col)) {
      if(any(floor(img) != img)) stop("image is not integer valued")
      else if(any(img < 1)) stop("image is not positive")
      else col <- 1:max(img)
    }
  }
  width <- nrow(img)
  height <- ncol(img)
  opar <- par(mar=c(0,0,0,0))
  on.exit(par(opar))
  image(1:width,1:height,img[,height:1],col=col,axes=F,asp=1,xlab="",ylab="")
}

#############################################################################

load("lab2_imgs.rda")
load("lab4_img.rda")