C2xyz.m

function [x,y,z] = C2xyz(C)
% C2XYZ returns the x and y coordinates of contours in a contour
% matrix and their corresponding z values. C is the contour matrix given by 
% the contour function. 
% 

%% Citing Antarctic Mapping Tools
% This function was developed for Antarctic Mapping Tools for Matlab (AMT). If AMT is useful for you,
% please cite our paper: 
% 
% Greene, C. A., Gwyther, D. E., & Blankenship, D. D. Antarctic Mapping Tools for Matlab. 
% Computers & Geosciences. 104 (2017) pp.151-157. 
% http://dx.doi.org/10.1016/j.cageo.2016.08.003
% 
% @article{amt,
%   title={{Antarctic Mapping Tools for \textsc{Matlab}}},
%   author={Greene, Chad A and Gwyther, David E and Blankenship, Donald D},
%   journal={Computers \& Geosciences},
%   year={2017},
%   volume={104},
%   pages={151--157},
%   publisher={Elsevier}, 
%   doi={10.1016/j.cageo.2016.08.003}, 
%   url={http://www.sciencedirect.com/science/article/pii/S0098300416302163}
% }
%   
%% Syntax
% 
%  [x,y] = C2xyz(C)
%  [x,y,z] = C2xyz(C)
% 
%% Description 
% 
% [x,y] = C2xyz(C) returns x and y coordinates of contours in a contour
% matrix C
% 
% [x,y,z] = C2xyz(C) also returns corresponding z values. 
% 
% 
%% Example
% Given a contour plot, you want to know the (x,y) coordinates of the contours, 
% as well as the z value corresponding to each contour line. 
%
% C = contour(peaks); 
% [x,y,z] = C2xyz(C);
% 
% This returns 1 x numberOfContourLines cells of x values and y values, and
% their corresponding z values are given in a 1 x numberOfContourLines
% array. If you'd like to plot a heavy black line along all of the z=0
% contours and a dotted red line along the z = -2 contours, try this: 
% 
% hold on; % Allows plotting atop the preexisting peaks plot. 
% for n = find(z==0); % only loop through the z = 0 values. 
%     plot(x{n},y{n},'k','linewidth',2)
% end
% 
% for n = find(z==-2) % now loop through the z = -2 values. 
%     plot(x{n},y{n},'r:','linewidth',2)
% end
% 
% * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
% Created by Chad Greene, August 2013. 
% 
% * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
% See also contour, contourf, clabel, contour3, and C2xy.


m(1)=1; 
n=1;  
try
    while n<length(C)
        n=n+1;
        m(n) = m(n-1)+C(2,m(n-1))+1; 
        
    end
end

for nn = 1:n-2
     x{nn} = C(1,m(nn)+1:m(nn+1)-1); 
     y{nn} = C(2,m(nn)+1:m(nn+1)-1); 
     if nargout==3
        z(nn) = C(1,m(nn));
     end
end

end