missing.R

# A quick function to save a PBM (http://en.wikipedia.org/wiki/Netpbm_format)
# visualize *a lot* of missing data pretty quickly (outside of R).

writeMissingPBM <- function(x, file) {
  dims <- dim(x)
  x[] <- as.integer(is.na(x))
  con <- file(file, open="wt")
  writeLines(sprintf("P1\n%d %d", ncol(x), nrow(x)), con)
  write.table(x, file=con, sep=" ", col.names=FALSE, row.names=FALSE, quote=FALSE)
  close(con)
}

# use this to save a file, then run:
# cat yourfile.pbm | pnmtopng > yourfile.png
# you will likely need to zoom in on large files.