matthiasm@8: function h = uimage(varargin)
matthiasm@8: %UIMAGE  Display image with uneven axis.
matthiasm@8: %   UIMAGE(X,Y,C) displays matrix C as an image, using the vectors X and
matthiasm@8: %   Y to specify the X and Y coordinates. X and Y may be unevenly spaced
matthiasm@8: %   vectors, but must be increasing. The size of C must be LENGTH(Y)*
matthiasm@8: %   LENGTH(X). (Most probably you'll want to display C' instead of C).
matthiasm@8: %
matthiasm@8: %   Contrary to Matlab's original IMAGE function, here the vectors X and Y
matthiasm@8: %   do not need to be linearly spaced. Whereas IMAGE linearly interpolates
matthiasm@8: %   the X-axis between X(1) and X(end), ignoring all other values (idem
matthiasm@8: %   for Y), UIMAGE allows for X and/or Y to be unevenly spaced vectors, by
matthiasm@8: %   locally stretching the matrix C (ie, by duplicating some elements of C)
matthiasm@8: %   for larger X and/or Y intervals.
matthiasm@8: %
matthiasm@8: %   The syntax for UIMAGE(X,Y,C,...) is the same as IMAGE(X,Y,C,...)
matthiasm@8: %   (all the remaining arguments, eg 'PropertyName'-PropertyValue pairs,
matthiasm@8: %   are passed to IMAGE). See IMAGE for details.
matthiasm@8: %
matthiasm@8: %   Use UIMAGESC to scale the data using the full colormap. The syntax for
matthiasm@8: %   UIMAGESC(X,Y,C,...) is the same as IMAGESC(X,Y,C,...).
matthiasm@8: %
matthiasm@8: %   Typical uses:
matthiasm@8: %      - Plotting a spatio-temporal diagram (T,X), with unevenly spaced
matthiasm@8: %      time intervals for T (eg, when some values are missing, or when
matthiasm@8: %      using a non-constant sampling rate).
matthiasm@8: %      - Plotting a set of power spectra with frequency in log-scale.
matthiasm@8: %
matthiasm@8: %   h = UIMAGE(X,Y,C,...) returns a handle to the image.
matthiasm@8: %
matthiasm@8: %   Example:
matthiasm@8: %     c = randn(50,20);         % Random 50x20 matrix
matthiasm@8: %     x = logspace(1,3,50);     % log-spaced X-axis, between 10 and 1000
matthiasm@8: %     y = linspace(3,8,20);     % lin-spaced Y-axis, between 3 and 8
matthiasm@8: %     uimagesc(x,y,c');         % displays the matrix
matthiasm@8: %
matthiasm@8: %   F. Moisy
matthiasm@8: %   Revision: 1.03,  Date: 2006/06/14.
matthiasm@8: %
matthiasm@8: %   See also IMAGE, IMAGESC, UIMAGESC.
matthiasm@8: 
matthiasm@8: 
matthiasm@8: % History:
matthiasm@8: % 2006/06/12: v1.00, first version.
matthiasm@8: % 2006/06/14: v1.03, minor bug fixed; works in ML6.
matthiasm@8: 
matthiasm@8: error(nargchk(3,inf,nargin));
matthiasm@8: 
matthiasm@8: % maximum number of matrix elements to interpolate the uneven axis
matthiasm@8: % (typically between 500 and 5000):
matthiasm@8: nmax = 2000; 
matthiasm@8: 
matthiasm@8: x = varargin{1};
matthiasm@8: y = varargin{2};
matthiasm@8: c = varargin{3};
matthiasm@8: 
matthiasm@8: if any(diff(x)<=0) || any(diff(y)<=0)
matthiasm@8:     error('The X and Y axis should be increasing.');
matthiasm@8: end
matthiasm@8: 
matthiasm@8: dx = min(diff(x));                   % smallest interval for X
matthiasm@8: dy = min(diff(y));                   % smallest interval for Y
matthiasm@8: 
matthiasm@8: % test if X and Y are linearly spaced (to within 10^-12):
matthiasm@8: evenx = all(abs(diff(x)/dx-1)<1e-12);     % true if X is linearly spaced
matthiasm@8: eveny = all(abs(diff(y)/dy-1)<1e-12);     % true if Y is linearly spaced
matthiasm@8: 
matthiasm@8: 
matthiasm@8: if evenx && eveny         % X and Y both evenly spaced
matthiasm@8: 
matthiasm@8:     xe = x;
matthiasm@8:     ye = y;
matthiasm@8:     ce = c;
matthiasm@8: 
matthiasm@8: elseif evenx && ~eveny    % X even and Y uneven
matthiasm@8:     
matthiasm@8:     nx = length(x);
matthiasm@8:     xe = x;
matthiasm@8: 
matthiasm@8:     ny = ceil(1 + (y(end) - y(1))/dy);   % number of points for Y
matthiasm@8:     ny = min(ny, nmax);
matthiasm@8:     ye = linspace(y(1), y(end), ny);
matthiasm@8: 
matthiasm@8:     ce = zeros(ny,nx);
matthiasm@8: 
matthiasm@8:     for j=1:ny
matthiasm@8:         indj = find(y<=ye(j));
matthiasm@8:         ce(j,1:nx) = c(indj(end), 1:nx);
matthiasm@8:     end;
matthiasm@8: 
matthiasm@8: elseif ~evenx && eveny    % X uneven and Y even
matthiasm@8:     
matthiasm@8:     nx = ceil(1 + (x(end) - x(1))/dx);   % number of points for X
matthiasm@8:     nx = min(nx, nmax);
matthiasm@8:     xe = linspace(x(1), x(end), nx);
matthiasm@8: 
matthiasm@8:     ny = length(y);
matthiasm@8:     ye = y;
matthiasm@8: 
matthiasm@8:     ce = zeros(ny,nx);
matthiasm@8: 
matthiasm@8:     for i=1:nx
matthiasm@8:         indi = find(x<=xe(i));
matthiasm@8:         ce(1:ny,i) = c(1:ny, indi(end));
matthiasm@8:     end;
matthiasm@8: 
matthiasm@8: elseif ~evenx && ~eveny   % X and Y both uneven
matthiasm@8:     
matthiasm@8:     nx = ceil(1 + (x(end) - x(1))/dx);   % number of points for X
matthiasm@8:     nx = min(nx, nmax);
matthiasm@8:     xe = linspace(x(1), x(end), nx);
matthiasm@8: 
matthiasm@8:     ny = ceil(1 + (y(end) - y(1))/dy);   % number of points for Y
matthiasm@8:     ny = min(ny, nmax);
matthiasm@8:     ye = linspace(y(1), y(end), ny);
matthiasm@8: 
matthiasm@8:     ce = zeros(ny,nx);
matthiasm@8: 
matthiasm@8:     for i=1:nx
matthiasm@8:         for j=1:ny
matthiasm@8:             indi = find(x<=xe(i));
matthiasm@8:             indj = find(y<=ye(j));
matthiasm@8:             ce(j,i) = c(indi(end), indj(end));
matthiasm@8:         end;
matthiasm@8:     end;
matthiasm@8: 
matthiasm@8: end
matthiasm@8: 
matthiasm@8: hh = image(xe, ye, ce, varargin{4:end});
matthiasm@8: 
matthiasm@8: if nargout>0
matthiasm@8:     h = hh;
matthiasm@8: end