Re: Plotting and Animating in Octave (vs. Matlab)

[Francesco Potortì]

>> Jeffrey wrote
>> I'm trying to make some plots and animations in Octave on a non-graphical
>> cluster. Is this even possible? With the first code, I can get a rough,
>> text-based plot. Is that the best I can do? Is there a way to animate (my
>> second code)? If not animate, can I at least create a movie?
>
>Have you considered writing the successive images to sequential files 
>and then use the  "animate" program (part of ImageMagick?)

On the same line, I have used this program of mine to generate a movie:


===File /home/work/math/octavelib/utils/movie.m=============
## Copyright (C) 2008, 2009 Francesco Potortì

## -*- texinfo -*-
## @deftypefn {Function File} {} movie (@var{action})
## @deftypefnx {Function File} {} movie (@var{action}, @var{mvf})
## @deftypefnx {Function File} {} movie (@var{action}, @var{mvf}, @var{rate})
## Create a movie from plots
##
## Example usage:
## @example
##   figure("visible","off"); movie("init","square.mp4")
##   n=100; a=zeros(n,n); a(1:20,41:60)=1;
##   for i=1:n; imshow(shift(a,i)); movie("add","square.mp4"); endfor
##   movie("close","square.mp4",24); close; system("totem square.mp4")
## @end example
##
## @var{action} takes one of three string values: @code{init},
## @code{add}, @code{close}. For each, @var{mvf} specifies the file name
## produced; the file name suffix sets the type of movie.
##
## If @var{mvf} is missing, it defaults to @file{octave_movie.mp4}. The
## suffix @file{.dir} creates a directory containing a png file per
## frame, the type @file{.zip} archives it using @command{zip}.  A
## suffix of @file{.mp4}, @file{.ogg}, @file{.mov}, @file{.mjpeg},
## @file{.avi}, @file{.flv} creates a movie using @command{ffmpeg};
## @file{.mng}, @file{.gif} create a movie using @command{convert}; type
## @file{.swf} creates a movie using @command{png2swf}. You must have
## the relevant program installed when using a given extension; no
## program is required for @file{.dir}.
##
## With the @var{close} action, a third arguments specifies the frame
## rate (defaulting to 5 frames/second).
##
## @end deftypefn

## Author: Francesco Potortì <address@hidden>
## Revision: 1.12
## License: GPL version 3 or later

function movie (action, mvf='octave_movie.mp4', rate=5)

  verbose = false;

  actions = {'init' 'add' 'close'};
  # gif swf
  types = {'.mp4' '.mng' '.gif' '.zip' '.ogg' '.swf' '.mov' ...
           '.mjpeg' '.avi' '.flv' '.dir'};
  if (nargin < 1 || !ischar(action) || !any(strcmp(action, actions)))
    error("first argument must be one of:%s", sprintf(" %s",actions{:}));
  endif
  if (nargin >= 2 && !ischar(mvf))
    error("second arg must be a string");
  endif
  [mpath mname mtype] = fileparts(mvf);

  mdir = fullfile(mpath, [mname '.d']);
  ppat =  '%06d.png';
  mpat = fullfile(mdir, ppat);
  mglob = fullfile(mdir, strrep(sprintf(ppat,0),'0','[0-9]'));
  fnof = fullfile(mdir, "+frame-number+");

  switch (action)
    case actions{1}             # init a movie
      if (isdir(mvf))
        cleandir(mvf, verbose)
      else
        unlink(mvf);
      endif
      while (!([allgood msg] = mkdir(mdir)))
        if (stat(fnof) && load(fnof).frameno == 0)
          error("while creating dir '%s': %s", mdir, msg);
        else
          cleandir(mdir, verbose);
        endif
      endwhile
      frameno = 0; save('-text',fnof,'frameno');
      if (verbose) printf("Directory '%s' created.\n", mdir); endif
    case actions{2}             # add a frame
      load(fnof);
      mfile = sprintf(mpat, ++frameno);
      print(mfile,'-dpng');
      save('-text',fnof,'frameno');
      if (verbose) printf("Frame '%s' added.\n", mfile); endif
    case actions{3}             # close the movie
      switch (mtype)
        case {types{[1 5 7 8 9 10]}} # mp4, ogg, mov, mjpeg, avi, flv
          cmd = sprintf("ffmpeg -y -r %d -sameq -i %s %s 2>&1", rate, mpat, 
mvf);
        case {types{[2 3]}}     # mng, gif
          cmd = sprintf("convert %s -adjoin %s %s 2>&1", mglob, mpat, mvf);
        case types{4}           # zip
          cmd = sprintf("zip -qr9 %s %s 2>&1", mvf, mglob);
        case types{6}           # swf
          cmd = sprintf("png2swf -z -r %d -o %s %s", rate, mvf, mglob);
        case types{end}         # dir
          rename(mdir, mvf); return
        otherwise
          error("second arg must end with one of:%s", sprintf(" %s",types{:}));
      endswitch
      [status output] = system(cmd);
      if (status != 0)
        load(fnof);
        error("Creation of movie '%s' containing %d frames failed:\n%s",
              mvf, frameno, output);
      endif
      if (verbose) printf("Movie '%s' contains %d frames:\n%s",
                          mvf, frameno, output); endif
      cleandir(mdir, verbose);
  endswitch
endfunction


function cleandir(mdir, verbose)
  unwind_protect
    save_crr = confirm_recursive_rmdir(false);
    [allgood msg] = rmdir(mdir,"s");
    if (!allgood)
      error("while removing dir '%s': %s", mdir, msg); endif
  unwind_protect_cleanup
    confirm_recursive_rmdir(save_crr);
  end_unwind_protect
  if (verbose) printf("Directory '%s' removed\n", mdir); endif
endfunction
============================================================

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