Question

How can I visualize a data set with a large amount of features using scatter3 plot in matlab. I already have it reduce to three features using PCA, but how do I get it to show up in different colours depending on if the y value (or labelled value) for the corresponding row is 1 or 0?
P.S. PCA return a [675 x 3] matrix, which is the 675 examples in the data set, with the first 3 principle components.

Answer 1

I’m not too up-to-date on my matlab, but I believe you can do it by firstly setting hold on then looping through and plotting each row of your matrix using plot3, and setting the colour based on the label. eg

hold on
for i=1:675,
    if (label == 1)
        plot3(mat(i,1), mat(i,2), mat(i,3), '-xr');
    elseif (label == 2)
        plot3(mat(i,1), mat(i,2), mat(i,3), '-og');
    elseif (label == 3)
        plot3(mat(i,1), mat(i,2), mat(i,3), '-b');
    end
end
hold off

This may need some tweaking though, since it is a while since I have used Matlab. Hope it helps 🙂