Ternary Plots

Zip file contains program to make different ternary plots.

Description

This zip files contains programs (five functions, one example program, and one sample data set) to plot data in ternary diagrams. The first option is a pseudo color plot, the second is a contour plot, and the third style plots the data as color coded symbols (similar to my function 'plot3c'). An additional function is provided to add labels.
The example program (termain.m) shows how to use the functions and how to modify the different plots.

• MATLAB release: MATLAB 6.5 (R13)
• Other requirements: Tested with Matlab R13

[Tanya Morton]

Very useful functionality & a good data set. I've used termain as a geophysics demonstration.
The files could be made slightly more robust to different output data (e.g. it errored with constant data)

[Jonathan Victor]

Basic functionality is OK, but there is a persistent "
Warning: Color Data is not set for Interpolated shading", and the default tickmarks are very closely spaced (when used in subplots)

[juan guillermo]

good

[Christoph Rudiger]

Great tool! Just what I was looking for. Also very well commented source code!

[Mary Piche]

If you try to plot (1,1,1) it is not the same location as seen with Origin 7 ... why?

[Jeremy Boyce]

change lines 52-57 to this:

if max(c1+c2+c3)>1
    c1old=c1;c2old=c2;c3old=c3;
    c1=c1./(c1old+c2old+c3old)
    c2=c2./(c1old+c2old+c3old)
    c3=c3./(c1old+c2old+c3old)
end

otherwise you end up using the normalized values to normalize the second and third steps.

[Benjamin Hauch]

Jeremy's changes are correct, but there is an additional correction that should be made, as c1 + c2 + c3 should always equal 1.
If input arguments sum to less than one but are not fractional, ternaryc will misrepresent data position because it only reads c1 and c2 for alignment. E.G., ternaryc(0.2,0.1,0.1) plots as though it is 20%, 10%, 70% instead of 50%, 25%, 25%.

To ensure the sum is 1, I added 2 lines and reformatted lines 52-57. New code looks at each line of input data and makes sure it is fractional. If not, fractional values are calculated.

totalc=zeros(size(c1,1),1);
for i=1:size(c1,1)
    if max(c1(i)+c2(i)+c3(i))~=1
        totalc(i)=c1(i)+c2(i)+c3(i);
        c1(i)=c1(i)./(totalc(i));
        c2(i)=c2(i)./(totalc(i));
        c3(i)=c3(i)./(totalc(i));
    end
end
clear totalc

[Olivia Cabrera]

very useful! however, i can't figure out how to change the tick intervals... please help. thanks