Arrays and different dimensions while saving outputs

Hello to everyone,

Say we have two for loops in the following form:

for i = [1, 2..., N_i]
    for j = [1, 2..., N_j]
        [Some code that does stuff];
        output = some_vector;  % This vector is of size m*1
        Array{i}(:, j) = output;
    end
end

So at the end, we will arrive with:

1. A cell array named Array with N_i elements.
2. Each element of the Array will display a matrix of m rows and N_j columns.

Now, this works fine if and only if the output has always the same size, i.e., m*1. We can't save matrices of different row lengths. So my question is the following: is there any way to store the outputs when they are of different size (e.g., the first loop gives an output of 10*1, and the second one of 15*1, and so on...)?

Thanks in advance to everyone.

Answer 1

[Dyuman Joshi]

"is there any way to store the outputs when they are of different size (e.g., the first loop gives an output of 10*1, and the second one of 15*1, and so on...)?"

Yes, Cell arrays -

m=5;
%pre-allocation
y=cell(m,1);
for p=1:m
    %Storing array of size dependent on the loop index
    y{p,1}=p*ones(p*m,1);
end
y

y = 5×1 cell array
    { 5×1 double}
    {10×1 double}
    {15×1 double}
    {20×1 double}
    {25×1 double}

y{3}

ans = 15×1

3 3 3 3 3 3 3 3 3 3

[Julio Maximiliano Ramirez Oyanarte]

Lol, this is embarassing, didn't know about the possibility of using {i, j} in arrays. Thanks!