Unnest cell array with nested cells to a cell array

How do I expand out an array with dimension '<100x1 cell>' in which each cell has a dimension '<1x11 cell>' into an array with dimension '<100x11 cell>'. Surely this must be straightforward? Thx

Answer 1

[Sean de Wolski]

% Sample Data
C = repmat({num2cell(1:11,1)},100,1);

% Unpacked
C2 = vertcat(C{:})

Unpack ( {:} ) it and use comma-separated list expansion in vertcat.

[SUSHMA MB]

But what if the dimensions are different. How do I expand out an array with dimension '<82794x1 cell>' in which each cell has different dimension like;

[1x12] double [1x18] double [1x6] double [1x14] double [1x6] double [1x10] double [1x6] double [1x8] double.....and so

[Boris]

Doesn't appear to work if the cell array contains cell arrays of empties ([]). Gives a single 1 column vertical cell array with most (but crucially not all) the elements......

Im my case, mycellarray has 1 x 26 cell array. Each of these cell arra6 has 709 by 1 cells. Several of these cell arrays are empty, some are partially empty. vertcat --> a cell array with 17018 x 1 cells, each with a single entry (many blank). However, 26*709 is 18434, not 17018...

Furthermore, if I transpose mycellarray (26 x 1 cells) then vertcat, I get the same result (17018 x 1 cells)... Must be hitting some kind of limit, I guess. Pity, as it is a pain to concatenate each cell array in mycellarray in a loop (or similar)...

[Boris]

Of course, it helps if you check that all the entries in the cell array are all cell arrays!

I had two cell array entries that were themselves arrays of doubles, not cell arrays and this is what was throwing the concatenation.

However, the very simple (horizontal) concatenation given by:

myflatcellarray=[mycellarray{:}];

seems to be marginally faster than horzcat...

Answer 2

[Gabor Bekes]

You might want something along the lines of:

a2 = {{'asdf',{'asdf','asdf',{'asdf'},{'asdf'},{'asdf',{'asdf'}},'asdf'},{'asdf',{'asdf'},{{'asdf'}}}},'asdf'}

while any(cellfun(@iscell,a2))
    a2 = [a2{cellfun(@iscell,a2)} a2(~cellfun(@iscell,a2))];
end

Now, you need to know in advance if you have a row, column or matrix layout cell array, and you need to use vertcat() for the latter two cases (logical indexing produces columns).

[Simon Matte]

Stumbled on this by googling a similar situation, wanted to add:

The previous solution works, but it also re-orders the elements in your cell array. Since it mattered in my specific case, I used this variant for my application:

    while any(cellfun(@iscell, a2))
        idx = cellfun(@iscell, a2);
        a2(idx) = a2{idx};
        a2(~idx) = a2(~idx);                            
    end

Answer 3

[Federico Canè]

wow, exactly what I needed. Thx