Combining multiple matrices into a single vector

Hi there,

have some matrices that I would like to combine into a single vector. For example:

T1 = [2 3;
      4 2]

T2 = [1 7;
      9 4]

T3 = [5 5;
      1 4]

I do not want to add them together like it does here:

T = [T1 T2 T3]

Rather I want to store them is such a way that I can index them in a loop

How can I accomplish this?

Many thanks

[Katy]

Hi Scott-

How do you want the final matrix to look? Can you provide an example of the desired final matrix?

Is it a single row? Or a combined matrix?

Thanks,

Katy

[Stephen23]

“How can I accomplish this?“

Either use a cell array or a 3D array.

Answer 1

[Star Strider]

A single vector is not possible, however a 3D array is with the cat function —

T1 = [2 3;
      4 2];

T2 = [1 7;
      9 4];

T3 = [5 5;
      1 4];

T = cat(3, T1, T2, T3)

T = 
T(:,:,1) =

     2     3
     4     2


T(:,:,2) =

     1     7
     9     4


T(:,:,3) =

     5     5
     1     4

T = reshape(T, 2, [])                           % Another Option

T = 2×6

2 3 1 7 5 5 4 2 9 4 1 4

EDIT — (29 Sep 2023 at 11:56)

Added the reshape option.

.

Answer 2

[Katy]

If I am understanding the question correctly, here's one way to store them as a single vector (T_vec).

It requires storing the inputs in a cell array rather than separate matrices.

Let me know if this solves your question!

T{1,1} = T1;
T{2,1} = T2;
T{3,1} = T3;

T_vec = [];
for i = 1:length(T)
    temp = T{i,1};
    sz_temp = size(temp);
    rows = sz_temp(1,1);
    col = sz_temp(1,2);
    for j = 1:rows
        for p = 1:col
            T_vec = [T_vec temp(j, p)];
        end
    end
end

[Voss]

@Katy: That can be simplified a bit:

T1 = [2 3;
      4 2];
T2 = [1 7;
      9 4];
T3 = [5 5;
      1 4];

T = {T1;T2;T3};
for ii = 1:numel(T)
    T{ii} = reshape(T{ii}.',1,[]);
end
T_vec = [T{:}]

T_vec = 1×12

2 3 4 2 1 7 9 4 5 5 1 4

Or, to simplify even further:

T = {T1;T2;T3};
T_vec = reshape(vertcat(T{:}).',1,[])

T_vec = 1×12

2 3 4 2 1 7 9 4 5 5 1 4