MATLAB: Having troubles with resizing matrices in ‘for loop’ and index search.

concatenationindexinglogical-arraysuneven vectors

I have a logical array of 0s an 1s. I would like to extract indices of all the cells with the value of 1, but without loosing information on columns. This gives a single column of indices.
idx = find(logical_array)
I tried for loop, but I'm not sure how to define my array before the for loop. Since the number of values varies between the columns, it generates a dimension mismatch error.
data = logical(randi(2,[10 3])-1);
idx = zeros(x,y);
for i = 1:y
    r_idx(:,i) = find(data(:,i));
end
It works when I generate separate vectors and concatenate them with padcat function. But is there an easier way?
   data = logical(randi(2,[10 3])-1);
    idx1 = find(data(:,1));
    idx2 = find(data(:,2));
    idx3 = find(data(:,3));
    idx = padcat(idx1, idx2, idx3);

Best Answer

[r, c] = find(logical_array)
This gives vectors of row and column indices.
I cannot tell what output you are hoping for.
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