ternaryc.m

function [hd,x,y]=ternaryc(c1,c2,c3,d,symbol)
%FUNCTION H=TERNARYC(C1,C2,C3,D,SYMBOL) plots the four data vectors C1,C2,C3, 
% and D color-coded in a ternary plot. The optional parameter SYMBOL
% determines the symbol used in the scatter plot.
% The first three vectors define the position of a data value within the
% ternary diagram, and the fourth vector will be plotted as a coloured
% symbol according to its magnitude. The marker symbol can be optionally
% defined by the marker parameter. If then, note that the marker symbol
% must be enclosed in single quotes (e.g., 'o'). If no symbol is specified
% a dot will be used.
%
% Calling the function with only the first three vectors, i.e.,
%      h=ternaryc(c1,c2,c3);
% results in a standard ternary plot. The data are plotted as a scatter
% plot in a ternary diagram with constant symbols (a blue diamond is the
% default value). To change the symbol (especially when plotting several
% data in one diagram) you can use the set command:
%      set(h,'markerfacecolor','r','marker','+')
%
% The ternary axis system must be created before using the terplot
% function. Axis label can be added using the terlabel function.
% The function returns two handels: hd can be used to modify the data
% points, and hcb is the handle of the colorbar.
%
% See also terplot, tersurf, terlabel, tercontour, and termain for a sample
% program showing the use of the ternary functions.
%
% Example:
%   close all;clear all
%   warning off MATLAB:griddata:DuplicateDataPoints
%   load limestone
%   % (The data file comes with the zip file).
%   figure
%   % Plot the ternary axis system
%   [h,hg,htick]=terplot;
%   % Plot the data
%   % First set the colormap (can't be done afterwards)
%   colormap(jet)
%   [hd,hcb]=ternaryc(A(:,1),A(:,2),A(:,3),A(:,4),'o');
%   %   or
%   [hd]=ternaryc(A(:,1),A(:,2),A(:,3));
%   %   for a constant value ternary plot.
%   % Add the labels
%   hlabels=terlabel('Limestone','Water','Air');
%
% Uli Theune, Geophysics, University of Alberta
% 2002 - 2005
%

% May 2005: added constant data plot option

if max(c1+c2+c3)>1
    c1=c1./(c1+c2+c3);
    c2=c2./(c1+c2+c3);
    c3=c3./(c1+c2+c3);
end
if nargin == 3
    % Constant data, set marker
    marker = 1;
else
    marker = 0;
    miv=min(d);
    mav=max(d);
    % If no marker specified use the default one
    if nargin==4
        symbol='.';
    end
    % Get the current colormap
    map=colormap;
end
% Plot the points
hold on
%XX = zeros(1,length(c1));
%YY = zeros(1,length(c1));

for i=1:length(c1)    
    x(i)=0.5-c1(i)*cos(pi/3)+c2(i)/2;
    y(i)=0.866-c1(i)*sin(pi/3)-c2(i)*cot(pi/6)/2;
    if marker == 1
        hd(i)=plot(x(i),y(i),'db','markerfacecolor','b');
    else
        in=round((d(i)-miv)*(length(map)-1)/(mav-miv));
        if in==0;in=1;end
        if in > length(map);in=length(map);end
        hd(i)=plot(x(i),y(i),symbol,'color',map(in,:),'markerfacecolor',map(in,:));
    end
    
    %XX(i) = x;
    %YY(i) = y;
end
hold off
axis image
% % Re-format the colorbar
% 
if marker == 0
    hcb=colorbar;
    
    %set(hcb,'ylim',[1 length(map)]);
    yal=linspace(0,1,10);
    set(hcb,'ytick',yal);
    % Create the yticklabels
    ytl=linspace(miv,mav,10);
    s=char(10,4);
    for i=1:10
        if abs(min(log10(abs(ytl)))) <= 3
            B=sprintf('%-4.3f',ytl(i));
        else
            B=sprintf('%-4.2E',ytl(i));
        end
        s(i,1:length(B))=B;
    end
    set(hcb,'yticklabel',s,'fontsize',9,'ycolor','k','xcolor','k');
end
%grid on
%set(get(h,'title'),'string',string,'fontweight','bold')