plotting 3-D data in 2-D

Hi again,

I have a 3D matrix (test=rand(3,3,4)) and I'm trying to plot each 2D entry through the third dimension [i.e. plot nine lines: (1,1,:),(1,2,:) and so on]. I'm not exactly sure how to do this, and can't get it to work with plot or plot3.

Any ideas?

Thanks,

Don

Answer 1

[Sean de Wolski]

test = repmat(magic(3),[1 1 4]);  %each vector into the third dimension will be the same (so we can verify accuracy)

test2 = reshape(permute(test,[3 2 1]),size(test,3),[]); %permute it and reshape it so that each column represents one vector into the third dimension

plot(test2) %plot it

[Donald]

Thank you for your help! As you probably have figured, I'm just starting out with Matlab.

[Donald]

Just a quick question:

Why is the [] necessary in the reshape command? What exactly is it doing?

[Sean de Wolski]

The [] indicates that we don't know how many entries are going to be in that dimension. So reshaping a 4x4 matrix into and 8x2 could be done with either

reshape(A,8,2) or reshape(A,[],2) or reshape(A,8,[]). In the above case there will be 9 columns (3x3) but I assume your test example is probably not the real size of your data so I generalized. It'll work with any sized matrix.

[Donald]

I've been fiddling around with this code and was wondering, is there a way to print the data from each row on a separate graphs? So for this 3x3 matrix have the output 3 charts with three lines each.

[Sean de Wolski]

doc subplot

and then a for loop to do the work.