%PLOTC Plot classifiers% %   PLOTC(W,S,LINE_WIDTH)%   PLOTC(W,LINE_WIDTH,S)% % Plots the discriminant as given by the mapping W on predefined axis,% typically set by scatterd. Discriminants are defined by the points% where class differences for mapping values are zero. %% S is the plot string, e.g. S = 'b--'. In case S = 'col' a color plot is% produced filling the regions of different classes with different colors.% Default S = 'k-';%% LINE_WIDTH sets the width of the lines and box. Default LINE_WIDTH = 1.5%% In W a cell array of classifiers may be given. In S a set of plot strings% of appropriate size may be given. Automatically a legend is added to% the plot.% % The linear gridsize is read from the global parameter GRIDSIZE, % default GRIDSIZE = 30.% % See also MAPPINGS, SCATTERD, PLOTM% Examples in PREX_CONFMAT, PREX_PLOTC% Copyright: R.P.W. Duin, duin@ph.tn.tudelft.nl% Faculty of Applied Sciences, Delft University of Technology% P.O. Box 5046, 2600 GA Delft, The Netherlands% $Id: plotc.m,v 1.9 2006/07/31 12:37:35 dick Exp $% REVISION HISTORY% DR1, Dick de Ridder, 31/07/2006% Fixed a divide by zero if the linear discriminant is perfectly vertical % (not a function).function handle = plotc(w,varargin)	prtrace(mfilename);	linew = 1.5;	s = [];	if nargin < 1 | isempty(w)		handle = mapping(mfilename,'combiner',s);		return	end	% Extract the plotwidth and linewidth:	for j = 1:nargin-1		if isstr(varargin{j})			s = varargin{j}; 		else			linew = varargin{j}; 		end	end	ss = char('k-','r-','b-','m-','k--','r--','b--','m--');	ss = char(ss,'k-.','r-.','b-.','m-.','k:','r:','b:','m:');	% When we want to plot a list of classifiers, we set up different	% plot strings ss and call plotc several times.	if iscell(w)		w = w(:);		n = length(w);		names = [];		% Check if sufficient plotstrings are available		if ~isempty(s)			if size(s,1) == 1				s = repmat(s,n,1);			elseif size(s,1) ~= n				error('Wrong number of plot strings')			end		else			s = ss(1:n,:);		end		% Plot the individual boundaries by calling 'mfilename' (i.e. this		% function again)		names = [];		hh = [];		for i=1:n			h = feval(mfilename,w{i},deblank(s(i,:)),linew);			hh = [hh h(1)];			names = char(names,getname(w{i}));		end		% Finally fix the legend:		names(1,:) = [];		legend(hh,names,0);		if nargout > 0			handle = hh;		end		return	end	% Now the task is to plot a single boundary (multiple boundaries are	% already covered above):	if ~isa(w,'mapping') | ~istrained(w)		error('Trained classifier expected')	end	[k,c] = size(w);	c = max(c,2);	if nargin < 2 | isempty(s)  % default plot string		s = 1;	end	%DXD: Stop when the classifier is not in 2D:	if (k~=2)		error('Plotc can only plot classifiers operating in 2D.');	end	if ~isstr(s)		if s > 16 | s < 1			error('Plotstring undefined')		else			s = deblank(ss(s,:));		end	end	% Get the figure size from the current figure:	hold on	V=axis;	hh = [];	set(gca,'linewidth',linew)	% linear discriminant	if isaffine(w) & c == 2 & ~strcmp(s,'col')	% plot as vector		d = +w;		n = size(d.rot,2);		if n == 2, n = 1; end		for i = 1:n			w1 = d.rot(:,i); w0 = d.offset(i);			x = sort([V(1),V(2),(-w1(2)*V(3)-w0)/w1(1),(-w1(2)*V(4)-w0)/w1(1)]);			x = x(2:3);%DR1			y = (-w1(1)*x-w0)/w1(2);			if (abs(w1(2)>eps))				y = (-w1(1)*x-w0)/w1(2);			else				y = [V(3) V(4)];			end;			h = plot(x,y,s);			set(h,'linewidth',linew)			hh = [hh h];		end	else    % general case: find contour(0)		% First define the mesh grid:		n = gridsize;		m = (n+1)*(n+1);		dx = (V(2)-V(1))/n;		dy = (V(4)-V(3))/n;		[X Y] = meshgrid(V(1):dx:V(2),V(3):dy:V(4));		D = double([X(:),Y(:),zeros(m,k-2)]*w);		if min(D(:)) >=0, D = log(D+realmin); end  % avoid infinities		% A two-class output can be given in one real number, avoid this		% special case and fix it:		if c == 2 & min(size(D)) == 1; D = [D -D]; end		c = size(D,2); 		if ~strcmp(s,'col')					% Plot the contour lines			if c < 3				Z = reshape(D(:,1) - D(:,2),n+1,n+1);				if ~isempty(contourc([V(1):dx:V(2)],[V(3):dy:V(4)],Z,[0 0]))					[cc h] = contour([V(1):dx:V(2)],[V(3):dy:V(4)],Z,[0 0],s);					set(h,'linewidth',linew)					hh = [hh;h];				end			else				for j=1:c-1					L = [1:c]; L(j) = [];					Z = reshape( D(:,j) - max(D(:,L),[],2),n+1,n+1);					if ~isempty(contourc([V(1):dx:V(2)],[V(3):dy:V(4)],Z,[0 0]))						[cc h] = contour([V(1):dx:V(2)],[V(3):dy:V(4)],Z,[0 0],s);						set(h,'linewidth',linew)						hh = [hh;h];					end				end			end		else			% Fill the areas with some colour:			col = 0; map = hsv(c+1); h = [];			for j=1:c				L = [1:c]; L(j) = [];				Z = reshape( D(:,j) - max(D(:,L)',[],1)',n+1,n+1);				Z = [-inf*ones(1,n+3);[-inf*ones(n+1,1),Z,-inf*ones(n+1,1)];-inf*ones(1,n+3)];				col = col + 1;				if ~isempty(contourc([V(1)-dx:dx:V(2)+dx],[V(3)-dy:dy:V(4)+dy],Z,[0 0]))					[cc h] = contour([V(1)-dx:dx:V(2)+dx],[V(3)-dy:dy:V(4)+dy],Z,[0 0]);					while ~isempty(cc)						len = cc(2,1);						fill(cc(1,2:len+1),cc(2,2:len+1),map(col,:),'FaceAlpha',0.5);						cc(:,1:len+1) = [];					end					hh = [hh;h];				end			end		end	end	axis(V);	% Return the handles if they are requested:	if nargout > 0, handle = hh; end	hold off	return