From octave-sources-request at bevo dot che dot wisc dot edu Tue Jun 24 08:23:54 2003
Subject: control contour levels
From: Fabian at isas-berlin dot de
To: octave-sources at bevo dot che dot wisc dot edu
Date: Tue, 24 Jun 2003 08:13:18 -0500

I needed better control over Gnuplot's 'set cntrparam' and 'set clabel'
commands from within Octave. The following function-script matches my
needs. 

It needs 'mat2str.m', which can be also be found on this list ( 2002 )
or in latest octave-forge package.

Rolf Fabian
<fabian at ISAS-Berlin dot de>




----------------- snip ------------------- snap ----------------------------------------

%USAGE	clevel( )			    ** NO REPLOT **
%	set default contour parameters	    
%
%	clevel( 's' )			    ** NO REPLOT **
%	show contour parameter settings
%
%	clevel( STR )                          ** REPLOT **
%	available STR :
%	'li'near               smooth
%	'bs'pline    	       smoother
%	'cu'bicspline          smoothest contours
%	'aNUM'                 number of automatic levels
%	'oNUM'	               order  NUM
%	'pNUM'	               points NUM
%	'no'	               same as 'unset clabel'
%	'yes'                  same as 'set clabel'
%	'%5.2f'                clabel format
%
%	clevel( VECTOR of z levels )           ** REPLOT **
%	replot with given 'discrete' contour levels
%
%ASSOC	Gnuplot commands :
%	set contour, set cntrparam, set clabel, set surface
%	Octave functions : graw, gsplot, contour.
%	Octave-forge     : 'mat2str.m' needed.
%
%NOTES  Instead of Gnuplots 'increment' option
%	"gset cntrparam levels increment <za>,<inc>,<zb>"
%	use:  clevel( <za>:<inc>:<zb> )
%
%Author	(C) 2003 Rolf Fabian <fabian at isas-berlin dot de> 030624
%	published under current  GNU GENERAL PUBLIC LICENSE

%030623	init


function clevel(arg)

if  nargin>1, usage( \
    "clevel(), clevel('s'), clevel(STRING), clevel(VECTOR)" );
endif

if  ~nargin	% set defaults

    % ------------------------------------------------ %
    % Current Gnuplot ( 3.8j ) defaults are
    % 'li'near, 5 points, order 4, 5 auto levels. 
    % By default, Label is on and label-format is '%8.3g'.

    % I personally prefer smoother contours by default!
    % Hence I use 'bs'pline mode.
    % A third possibility is 'cu'bicsplines.

    SMOOTH='bs';	% Select from 'li','bs','cu'
    POINTS= 5;		% see Gnuplot help
    ORDER = 4;		% see Gnuplot help
    LEVELS= 5;		% 'auto'matic levels
    LABFMT='%8.3g';	% Label-format
    LABEL = 1;		% switch off: change to 0 
    % ------------------------------------------------ %

    graw( sprintf('set cntrparam %s\n',       SMOOTH) );
    graw( sprintf('set cntrparam p %d\n',     POINTS) );
    graw( sprintf('set cntrparam o %d\n',     ORDER ) );
    graw( sprintf('set cntrparam le au %d\n', LEVELS) );

			% always set to default format 
			% even if LABEL=0 (switched off)
    graw( sprintf("set clabel '%s'\n", LABFMT) );

    if ~LABEL		% switch off
       graw( "unset clabel '%s'\n" );
    endif

else

    L = length( arg );

    if  isstr( arg )

	arg = tolower( arg );

	if  L==1 && arg=='s'
	    graw('show cntrparam\n');    return;

	elseif arg(1)=='a'	% auto levels NUM
	    NUM= str2num( arg(2:length(arg)) )
	    graw( sprintf( 'set cntrparam le au %d\n',NUM) );

	elseif arg(1)=='o'	% smooth order NUM
	    NUM= str2num( arg(2:length(arg)) );
	    graw( sprintf( 'set cntrparam or %d\n',NUM) );

	elseif arg(1)=='p'	% points NUM
	    NUM= str2num( arg(2:length(arg)) );
	    graw( sprintf( 'set cntrparam po %d\n',NUM) );

	elseif arg(1)=='%'	% clabel format
    	    graw( sprintf( "set clabel '%s'\n", arg) );

	elseif L==2 && arg=='no'   % switch-off clabel
    	    graw( sprintf( "unset clabel\n") );

	elseif L==3 && arg=='yes'  % switch-on clabel
				   % using previous format
    	    graw( sprintf( "set clabel\n") );

	else
	    if     arg(1:2)=='li', graw('set cntrparam li\n');
	    elseif arg(1:2)=='bs', graw('set cntrparam bs\n');
	    elseif arg(1:2)=='cu', graw('set cntrparam cu\n');
	    else   error(\
		"clevel: unknown argument \'%s\'",arg);
            end
	end

	replot;

    elseif isvector( arg )

	arg=arg(:).';		% prepare for 'mat2str'

	if iscomplex( arg )
	   error( "clevel: complex z-levels invalid." );
	endif

	z = mat2str( arg );
   	if L>1
	   z( length(z) )='';	% rm '[' and ']'
	   z( 1 )='';
	endif

	graw( sprintf("set cntrparam lev dis %s\n", z ) );

	replot;

   else	error( "clevel: invalid argument." );
   endif

endif

endfunction

%!demo
%! clevel;   % init with defined settings
%! clevel('s')                % show them
%! graw('set size square\n');
%! title('default'); 
%! N=15; contour( randn(N) ); % plot
%! W = 5;    % pause W seconds
%! pause(W); s='linear'; title(s); clevel(s)
%! pause(W); s='cubics'; title(s); clevel(s)
%! pause(W); s='o2';     title(s); clevel(s)
%! pause(W); s='p3';     title(s); clevel(s)
%! pause(W); title('increment');
%!           clevel( -0.5:0.25:0.5 )
%! pause(W); title( 'discrete' );
%!           clevel( [-0.123,-0.1,0.1,+0.34] )
%! pause(W); s= '%.3f';       title(s);            clevel( s )
%! pause(W); title( 'switch off labels' );         clevel('no')
%! pause(W); title( 'restore labels  at prev dot  FMT' ); clevel('yes')
%! title(''); clevel;    % back to defaults
%! graw('set size nosquare\n');