%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, that
% can be set by the function gridsize: for instance 'gridsize(100)'
% default gridsize is 30. As all these points have to be classified (e.g.
% 100x100) this always done in batch mode. If needed desired the default
% batch size may be changed by PRGLOBAL.
%
% Examples in PREX_CONFMAT, PREX_PLOTC
%
% SEE ALSO (<a href="http://37steps.com/prtools">PRTools Guide</a>)
% MAPPINGS, SCATTERD, PLOTM, GRIDSIZE, SETBATCH, PRGLOBAL
% 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 1.6 2009/10/30 11:01:47 davidt Exp $
function handle = plotc(w,varargin)
linew = 1.5;
s = [];
if nargin < 1 | isempty(w)
handle = prmapping(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,'prmapping') | ~istrained(w)
error('Trained classifier expected')
end
%w = w*setbatch; % Avoid memory prolems with large gridsizes
[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);
J = find(w1==0);
if ~isempty(J)
w1(J) = repmat(realmin,size(J));
end
x = sort([V(1),V(2),(-w1(2)*V(3)-w0)/w1(1),(-w1(2)*V(4)-w0)/w1(1)]);
if (x(1)==x(2)) % for exactly vertical lines...
y = V(3:4);
else
y = (-w1(1)*x-w0)/w1(2);
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)
%DXD Matlab 7 has different handle definitions:
if str2num(version('-release'))>13,
h = get(h,'children');
end
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)
%DXD Matlab 7 has different handle definitions:
if str2num(version('-release'))>13,
h = get(h,'children');
end
hh = [hh;h];
end
end
end
else
% Fill the areas with some colour:
col = 0; mapp = 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);
h = [h;fill(cc(1,2:len+1),cc(2,2:len+1),mapp(col,:),'FaceAlpha',0.5)];
%fill(cc(1,2:len+1),cc(2,2:len+1),mapp(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