plotg.m

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function h = plotg(grid,z,nrc)
%PLOTG Plot the function values z on a 2D grid
%
%    h = plotg(grid,z)
%
% Plot the function values given in z on the 2D grid. The grid is a
% 2xN dataset, where N is nxn. Vector z has therefore also length N.
%
%    h = plotg(grid,z,clrs)
%
% By setting clrs the number of colors can be changed (default
% clrs=10).
%
% When you already have a PRTools mapping w, please use plotw(w).
%
% see also: makegriddat, gendatgrid, plotw

% Copyright: D. Tax, R.P.W. Duin, [e-mail]
% Faculty of Applied Physics, Delft University of Technology
% P.O. Box 5046, 2600 GA Delft, The Netherlands

if nargin<3
  nrc = 10;
end

% I want to be able to handle datasets
if isa(grid,'dataset')
  grid = +grid;
end
if isa(z,'dataset')
  z = +z;
end

% first determine the sizes of the grid:
lx = length(find(grid(:,2)==grid(1,2)));
ly = size(grid,1)/lx;
% and extract the exact x and y positions:
x = grid(1:ly:end,1);
y = grid(1:ly,2)';

% see if z has the right size
if (size(z,2)>2)
  error('Data z does not have appropriate size');
end
if (size(z,2)==2)
  z = z(:,1) - z(:,2);
  [c,h] = contourf(x,y,reshape(+z,ly,lx),nrc);
  hold on;
  [c2,h2] = contour(x,y,reshape(+z,ly,lx),[0 0]);
  set(h2,'linewidth',2,'edgecolor','w');
else
  hold on;
  [c,h] = contourf(x,y,reshape(+z,ly,lx),nrc);
end

if nargout==0
  clear h;
end

return