MATLAB compatible subplot()

[Vinayak Dutt]

Hi :

Here's completely MATLAB compatible subplot() function.
Ealier there was still some incompatibility between my subplot()
and MATLAB's subplot() as pointed out by Rick Niles.

This differs from my ealier version in the sense that earlier
the calling interface was:

subplot(columns,rows,plot_index)

and now its

subplot(rows,columns,plot_index)

which is in line with MATLAB subplot() command.

Hope, its useful to Octave users.

-vinayak dutt-
-ultrasound research-
-mayo clinic-

%
%  ------------ file: subplot.m ------------
%

function subplot (rows, columns, index)

% usage: subplot (rows,columns,index)
%        or 
%        subplot(rcn)
%
% NOTE: this will work only with gnuplot installed with
%       multiplot patch (or version 3.6 beta)
%
%    Sets gnuplot in multiplot mode and plots in location
%    given by index (there are columns X rows subwindows)
%
%    Input:
%
%    rows   : number of rows in subplot grid
%    columns: number of columns in subplot grid
%    index  : index of subplot where to make the next plot
%
%    If only one arg, then it (crn) has to be three digit 
%    value specifying the location in digit 1 (rows) and 
%    2 (columns) and digit 3 is the plot index
%
%    The plot index runs row-wise,i.e., first all the
%    columns in a row are filled and then the next
%    row is filled
%
%    For example, plot with 4 X 2 grid, will have
%    plot indices running as follows:
%
%      -----------------------------------
%      |        |       |       |        |
%      |    1   |    2  |    3  |    4   |
%      |        |       |       |        |
%      -----------------------------------
%      |        |       |       |        |
%      |    5   |    6  |    7  |    8   |
%      |        |       |       |        |
%      -----------------------------------
%

%
% global variables to keep track of multiplot options
%
  global multiplot_mode 
  global multi_xn multi_yn
  global multi_xsize multi_ysize 

% check calling argument count

  if (nargin != 3 && nargin != 1)
        error "usage: subplot (rows,columns,index) or subplot(rcn)"
  endif

% check for scalar inputs

  if( nargin == 1 )
        if (!is_scalar(rows))
                error ("subplot: input rcn has to be a scalar");
        endif
        xnp = rows;
        rows = fix(xnp/100);
        columns = fix((xnp - 100*rows)/10);
        index = xnp - 10*columns - 100*rows;
  else
        if (!(is_scalar(columns) && is_scalar(rows) && is_scalar(index)))
                error ("subplot: columns, rows, and index  have to be scalars");
        endif
  endif
  columns = fix(columns);
  rows = fix(rows);
  index = fix(index);

  if (index > columns*rows)
        error ("subplot: index must be less than columns*rows");
  endif;

  if( columns < 1 || rows < 1 || index < 1)
        error ("subplot: columns,rows,index must be be positive");
  endif;

  if((columns*rows) == 1)
%
% switching to single plot ?
%
        set nomultiplot;
        set size 1,1
        set origin 0,0
        multi_xn = 1;
        multi_yn = 1;
        multiplot_mode = 0;
        return;
  endif;
%
% doing multiplot plots
%
   doagain = 0;
   if ( exist ("multiplot_mode") != 1 )
        doagain = 1;
   else 
        if ( (multiplot_mode != 1) || (multi_xn != columns) || (multi_yn != 
rows) )
                doagain = 1;
        endif;
   endif;
   if ( doagain )
        multiplot_mode = 1;
        multi_xn = columns;
        multi_yn = rows;
        multi_xsize = 1.0 ./ columns;
        multi_ysize = 1.0 ./ rows;
        set multiplot;
        command = sprintf ("set size %g,%g", multi_xsize,multi_ysize);
        eval (command);
   endif;
%
% get the sub plot location
%
  yp = fix((index-1)/columns);
  xp = index - yp*columns - 1;
  xp = xp + 1;
  yp = yp + 1;
%
% set the origin
%
  xo = (xp - 1.0)*multi_xsize;
  yo = (rows - yp)*multi_ysize;
  command = sprintf ("set origin %g,%g", xo,yo);
  eval (command);
%
endfunction