raster.data.table

as.data.table.raster <- function(x, row.names = NULL, optional = FALSE, xy=FALSE, inmem = canProcessInMemory(x, 2), ...) {
  stopifnot(require("data.table"))
  if(inmem) {
    v <- as.data.table(as.data.frame(x, row.names=row.names, optional=optional, xy=xy, ...))
  } else {
    tr <- blockSize(x, n=2)
    l <- lapply(1:tr$n, function(i) 
      as.data.table(as.data.frame(getValues(x, 
                                            row=tr$row[i], 
                                            nrows=tr$nrows[i]), 
                                  row.names=row.names, optional=optional, xy=xy, ...)))
    v <- rbindlist(l)
  }
  coln <- names(x)
  if(xy) coln <- c("x", "y", coln)
  setnames(v, coln)
  v
}

if (!isGeneric("as.data.table")) {
  setGeneric("as.data.table", function(x, ...)
    standardGeneric("as.data.table"))
}  

setMethod('as.data.table', signature(x='data.frame'), data.table::as.data.table)
setMethod('as.data.table', signature(x='Raster'), as.data.table.raster)