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matlabcell

Best way to count all elements in a cell array?

I want to count all elements in a cell array, including those in "nested" cells.

For a cell array

>> C = {{{1,2},{3,4,5}},{{{6},{7},{8}},{9}},10}

C = {1x2 cell}    {1x2 cell}    [10]

The answer should be 10.

One way is to use [C{:}] repeatedly until there are no cells left and then use numel but there must be a better way?

Solution

  • Since you are only interested in the number of elements, here is a simplified version of flatten.m that @Ansari linked to:

    function n = my_numel(A)
    n = 0;
    for i=1:numel(A)
        if iscell(A{i})
            n = n + my_numel(A{i});
        else
            n = n + numel(A{i});
        end
    end
end

    The result:

    >> C = {{{1,2},{3,4,5}},{{{6},{7},{8}},{9}},10};
>> my_numel(C)
ans =
    10

    EDIT:

    If you are feeling lazy, we can let CELLPLOT do the counting:

    hFig = figure('Visible','off');
num = numel( findobj(cellplot(C),'type','text') );
close(hFig)

    Basically we create an invisible figure, plot the cell array, count how many "text" objects were created, then delete the invisible figure.

    This is how the plot looks like underneath:

    screenshot