Converting matirx into vektor inside a cell array

Hello,

I have a cell array V (1024x1280 cells).

In every cell of this cell array I saved a 2x2 matrix.

Now i want to split this matrix into two column vectors and save these vectors in two cell arrays ev1 and ev2.

And all this for the entire cell array V.

I had the following idea:

for i=1:n
    for j=1:m
        [ev1{j,i}] = V{j,i}(1,1); 
        [ev2{j,i}] = V{j,i}(1,2);
    end
end

But with this I only get single values.

Thanks,

Antonio

Answer 1

[Alex Mcaulley]

Try with this:

for i=1:n
    for j=1:m
        ev1{j,i} = V{j,i}(:,1); 
        ev2{j,i} = V{j,i}(:,2);
    end
end

[Antonio Sarusic]

Thanks, this is working!

Answer 2

[the cyclist]

ev1 = cellfun(@(x)x(:,1),V,'UniformOutput',false);
ev2 = cellfun(@(x)x(:,2),V,'UniformOutput',false);

[Antonio Sarusic]

This somehow doesn't compute...

[the cyclist]

That's odd. It worked for a test array that mimicked what you described.

If you want to upload your cell array V, I could poke around. But at least you have a solution.

[Antonio Sarusic]

The cell array V is to big to upload.

But here ist the matrix I started with and the code I hade until this point:

[m,n]=size(Bild);

[Gx,Gy] = imgradientxy(Bild);
[Gxx,Gxy] = imgradientxy(Gx);
[Gyx,Gyy] = imgradientxy(Gy);

for i=1:n
    for j=1:m
      HesseM = [Gxx(j,i) Gxy(j,i); Gyx(j,i) Gyy(j,i)];
      [V{j,i},D{j,i}] = eig(HesseM);
    end
end

for i=1:n
    for j=1:m
        ev1 = cellfun(@(x)x(:,1),V,'UniformOutput',false);
        ev2 = cellfun(@(x)x(:,2),V,'UniformOutput',false);
    end
end

[the cyclist]

Sorry, I don't have the Image Processing Toolbox, so I think we are at an impasse. :-/

[the cyclist]

I will say this, though. It looks like you could use 4-dimensional arrays instead of cell arrays.

V = zeros(m,n,2,2);
D = zeros(m,n,2,2);

for i=1:n
    for j=1:m
    HesseM = [Gxx(j,i) Gxy(j,i); Gyx(j,i) Gyy(j,i)];
    [V(j,i,:,:),D(j,i,:,:)] = eig(HesseM);
    end
end

Then the next operation is ...

ev1 = V(:,:,:,1);
ev2 = V(:,:,:,2);

and other downstream operations might also be easier, and probably execute faster.

[Antonio Sarusic]

Ok. I'll give it a try.

Thank you!