open Printf
open ExtLib

let vtk = "test.vtk";;


let stream_filter p stream =
        let rec next i =
                try
                        let value = Stream.next stream in
                        if p value then Some value else next i
                with Stream.Failure -> None in
        Stream.from next;;



let grabVtkSizeInfo path =
        let ic = open_in path in
        let lineStream = Stream.from (fun _ ->
                try Some (input_line ic) with End_of_file -> None) in
        let s = (stream_filter (fun s -> String.exists s "DIMENSIONS") lineStream) in
        try Some (Stream.next s) with Stream.Failure -> None;;




let pgm = "test.pgm";;

let oc = open_out pgm;;

let info = Option.default "" (grabVtkSizeInfo "140408aX_t01_ch01.vtk");;

fprintf oc "P2\n%d %d\n%d\n%s" 5 5 255 info;;