Problems with different length vectors introduction into an array

Good morning, I have dimensioning problems with the following loop:

for i = 1:rows
    for j = 1:columns
        if vimage(i,j) ~=1
            for z = 1:(colors-1)
                if vimage(i,j) >= content_coords(z,3) && vimage(i,j) < content_coords((z+1),3)
                    real_content(i,j,:) = content_coords(z,4):0.1:content_coords(z,5);   
                elseif vimage(i,j) >= content_coords(colors,3)
                    real_content(i,j,:) = content_coords(colors,4):0.1:content_coords(colors,5); 
                end
            end
        else
            real_content(i,j,:) = NaN; %or do nothing
        end  
    end
end

vimage corresponds to a 300*300 array with different values

The third column (3) of content_coords contains the values to be compared with those in vimage, then the fourth (4) and the fifth column (5) contain a minimum and a maximum value respectively.

Even tho all the maximums and minimums are 0.1 multiples, the length of content_coords(z,4):0.1:content_coords(z,5) is different depending on the case.

The problem comes when using (i, j, :) which leads to the following error: "Unable to perform assignment because the size of the left side is 1-by-1-by-5 and the size of the right side is 1-by-5."

I've tried to create real_content array with Nan prior to the execution with the maximum dimensions but still not working.

Thank you in advance for your help and time.

Gonzalo.

Answer 1

[Ameer Hamza]

In MATLAB, you cannot save data of varying dimensions in a simple array. You need to use cell array if the dimension of data is changing.

real_content = cell(rows, columns); % initialize

%% code of for-loops
    real_content{i,j} = content_coords(z,4):0.1:content_coords(z,5);

[Gonzalo Molina]

Thank you so much Ameer, that is exactly what I needed.

Just one more question:

Which would be the best way to introduce a NaN vector of the maximum length for the "else" condition?

[Ameer Hamza]

Do you know the maximum length? If yes, then you can write

real_content{i,j} = nan(1,max_length); %or do nothing

[Gonzalo Molina]

Perfect, thank you very much.

Have a nice day.

[Ameer Hamza]

I am glad to be of help!