How can I concatenate matrices with different dimensions in a cell array to a numeric array?

Hello everybody,

I have a cell array, C:

celldisp(C);

C{1} =

   NaN

C{2} =

        2068        2069

C{3} =

        2300        2301        2302        2303

C{4} =

   NaN

in which each cell has different dimensions (as you can see, some cells contain NaN's). I wish to convert this cell to a 1-row numeric array (A), which would look like:

A = [NaN 2068 2069 2300 2301 2302 2303 NaN]

Thank you!

Answer 1

[Adam]

cell2mat(C);

Note though that this will only work if all cells of c contain row arrays as in your example. If there are also column arrays or randomly sized arrays a different solution is required.

If that is the case you should amend your example to ensure it covers the most complex case you wish to solve since providing a solution that over-solves the problem is a waste of time, hence the above works in the case you showed, but not in any generalised case.

[Henry Hallock]

Thank you for your answer, Adam. This produces the following error message:

cell2mat(C); Error using cat Dimensions of matrices being concatenated are not consistent.

Error in cell2mat (line 83) m{n} = cat(1,c{:,n});

Thanks!

[Adam]

Are you using it on the data you gave in the first post? Because that is the data I typed in for each cell, resulting in:

>> celldisp(c)
c{1} =
 NaN
c{2} =
      2068        2069
c{3} =
      2300        2301        2302        2303
c{4} =
 NaN

followed by:

>> cell2mat( c )
ans =
       NaN        2068        2069        2300        2301        2302        2303         NaN

[Henry Hallock]

Aha! My original 'C' was a 4x1 cell - when I transposed it, this solution worked perfectly. Thank you!

Answer 2

[Guillaume]

If you get an error with a plain cell2mat, that is because some of the cells are not row vector as Adam suggested.

This will flatten the content of all the cells, so will work regardless the content of the cell, be it a column or row vector or a matrix of any dimension:

c = {1, [2 3 4], [5 7 9; 6 8 9], [10 11 12]'}; %for example
cell2mat(cellfun(@(m) m(:).', c, 'UniformOutput', false))