MATLAB: Find values in an cell array

cell arrays

Hi all,
I have an cell array that is like the one in the screenshot (see attached file).
I would like to find in each row, how many times value 1,2,3..etc exists
Could you help me with that?
thanks in advance!
Nikolas

Best Answer

  • cell_rows = arrayfun(@(ROW) horzcat(YourCell{ROW,:}), 1:size(YourCell,1), 'uniform', 0);
    all_values = horzcat(cell_rows{:});
    [G, uvals] = findgroups(all_values);
    num_vals = length(uvals);
    row_lens = cellfun(@length, cell_rows);
    G_by_row = mat2cell(G, 1, row_lens);
    counts = cellfun(@(R) [uvals(:), accumarray(R(:), 1, [num_vals 1])], G_by_row, 'uniform', 0);
    The result will be a cell array with 63 entries. Each entry will be an N x 2 table, where N is the number of unique values over the entire matrix (not the number of unique for the individual row.) The first column will be the list of unique values; this will be the same for all of the arrays. The second column will be the counts for the corresponding values.
    This will work even if the values stored in the array are not positive integers. It will even work if the values are not integers; however in the way it is written, it will consider two values to be different if they differ in even a single bit (so if the values were calculated and there might be round-off, there could be a problem.)
    If you know that the values are all positive integers in the range 1 to something (such as 50) then the code can be simplified.