Ternary plot (Contour lines)

Hi, I am trying to draw some contour lines of a ternary phase diagram. I am currently just using closely spaced digitized points on the ternary plot. I am using the package: Ternary Plots. However, I want smooth lines connecting them. So far, I have this:

The code is:

B = readmatrix('dataset.xlsx');
close all
clc
B1 = B*0.01; %liquidus line

fig = figure('units','pixels','position',[100 100 1000 800]);

colormap(jet)
%-- Plot the axis system
[h,htick]=terplot3;

hter1=ternaryc(B1(1:188,1),B1(1:188,2),B1(1:188,3)); %phase boundaries
set(hter1,'marker','o','markerfacecolor','none','markersize',4)

hlabels=terlabel2('MnO','Al_2O_3','SiO_2');

The dataset is here. Thanks for any help.

Answer 1

[Milan Bansal]

Hi Angshuman Podder,

I understand that you wish to plot the smooth contour lines instead of marker points in the ternary phase diagram.

To achieve this, you can modify the code in the function "ternaryc" to enable plotting the lines instead of marker points as shown in the following code snippet.

function [hd,hcb]=ternaryc(c1,c2,c3,d,symbol)

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 line drawing instead of marker
    marker = 1;
else
    marker = 0;
    miv=min(d);
    mav=max(d);
    % If no marker specified use the default one
    if nargin==4
        symbol='-';  % Default is a line ('-')
    end
    % Get the current colormap
    map=colormap;
end

% Plot the points as continuous lines
hold on
x = 0.5 - c1*cos(pi/3) + c2/2; % X-coordinates for ternary plot
y = 0.866 - c1*sin(pi/3) - c2*cot(pi/6)/2; % Y-coordinates for ternary plot

if marker == 1
    %%%% Plot continuous lines instead of points %%%%
    hd = plot(x, y, '-b', 'LineWidth', 1.5); % Blue line with width 1.5
else
    % Use the color map for colored lines
    for i=1:length(c1)-1
        in=round((d(i)-miv)*(length(map)-1)/(mav-miv));
        if in==0;in=1;end
        if in > length(map);in=length(map);end
        % Plot a colored segment between consecutive points
        hd(i)=plot(x(i:i+1), y(i:i+1), 'color', map(in,:), 'LineWidth', 1.5);
    end
end
hold off

axis image

% % Re-format the colorbar if marker is disabled
if marker == 0
    hcb=colorbar;
    yal=linspace(0,1,10);
    set(hcb,'ytick',yal);
    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

You will also need to remove the following line from your code to disable plotting of markers.

set(hter1,'marker','o','markerfacecolor','none','markersize',4)

Here is the output plot after making these changes.

Refer to the documentation to learn more about different options in plot function.

https://www.mathworks.com/help/matlab/ref/plot.html#btzitot-2

Hope this helps!