Combine a cell array of cell arrays to a cell array of numbers

Question

Eduardo 2014-1-20

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/113029-combine-a-cell-array-of-cell-arrays-to-a-cell-array-of-numbers

编辑： per isakson 2014-1-21

采纳的回答： Matt J

在 MATLAB Online 中打开

Hi,

I have a dynamic cell array of cell arrays and I want to combine it into a cell array of data.

For example:

kdata =

Columns 1 through 4
    {10x3 cell}    {10x3 cell}    {10x3 cell}    {10x3 cell}
Columns 5 through 8
    {10x3 cell}    {10x3 cell}    {10x3 cell}    {10x3 cell}
Columns 9 through 10
    {10x3 cell}    {10x3 cell}

What I want:

kdata_combined =

Columns 1 through 11
    '8'    '7'    '2'    '8'    '10'    '5'    '1'    '2'    '1'    '4'    '3'
    '2'    '1'    '4'    '2'    '3'     '0'    '3'    '3'    '0'    '0'    '0'
    '1'    '1'    '1'    '4'    '4'     '4'    '1'    '1'    '2'    '4'    '2'
    '3'    '2'    '1'    '1'    '2'     '1'    '1'    '1'    '0'    '2'    '2'
    '2'    '5'    '0'    '0'    '1'     '2'    '0'    '2'    '0'    '1'    '0'
    '0'    '1'    '3'    '1'    '1'     '2'    '1'    '0'    '0'    '2'    '1'
    '0'    '4'    '0'    '0'    '1'     '0'    '1'    '2'    '1'    '1'    '0'
    '2'    '0'    '0'    '0'    '0'     '0'    '0'    '0'    '1'    '0'    '0'
    '2'    '0'    '0'    '1'    '0'     '1'    '2'    '0'    '0'    '3'    '0'
    '0'    '0'    '1'    '0'    '1'     '0'    '1'    '0'    '2'    '2'    '1'
Columns 12 through 22
    '11'    '0'    '2'    '11'    '6'    '7'    '6'    '0'    '5'    '0'    '4'
    '2'     '7'    '2'    '1'     '1'    '4'    '6'    '2'    '0'    '5'    '3'
    '2'     '1'    '1'    '1'     '1'    '4'    '3'    '1'    '2'    '3'    '0'
    '2'     '1'    '2'    '1'     '1'    '4'    '0'    '1'    '0'    '1'    '2'
    '2'     '0'    '1'    '1'     '1'    '0'    '2'    '1'    '1'    '1'    '3'
    '0'     '0'    '0'    '3'     '0'    '4'    '0'    '0'    '0'    '0'    '1'
    '3'     '2'    '1'    '2'     '2'    '0'    '2'    '0'    '0'    '0'    '1'
    '2'     '0'    '3'    '0'     '1'    '2'    '0'    '2'    '1'    '1'    '0'
    '1'     '0'    '1'    '1'     '0'    '0'    '2'    '0'    '2'    '0'    '0'
    '0'     '0'    '0'    '2'     '2'    '0'    '1'    '3'    '0'    '0'    '0'
Columns 23 through 30
    '1'    '1'    '3'    '1'    '2'    '4'    '5'    '8'
    '0'    '0'    '5'    '4'    '0'    '2'    '2'    '7'
    '1'    '1'    '3'    '9'    '0'    '0'    '4'    '0'
    '3'    '1'    '1'    '0'    '3'    '0'    '0'    '1'
    '3'    '1'    '0'    '0'    '0'    '1'    '1'    '0'
    '3'    '1'    '0'    '1'    '0'    '1'    '0'    '2'
    '1'    '0'    '0'    '1'    '1'    '0'    '1'    '0'
    '7'    '1'    '0'    '0'    '0'    '1'    '1'    '1' 
    '0'    '0'    '2'    '1'    '2'    '0'    '3'    '1' 
    '4'    '0'    '1'    '0'    '2'    '0'    '2'    '0'

I want to do this without any 'for' because my cell arrays are too big. And I can't concat them manually because I never know the size.

Is there anyway I can do this using some function like cell fun ?

Thanks.

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per isakson 2014-1-21

编辑：per isakson 2014-1-21

How do you know they "are too big" to use a loop?

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Answer 1

Matt J 2014-1-20

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https://ww2.mathworks.cn/matlabcentral/answers/113029-combine-a-cell-array-of-cell-arrays-to-a-cell-array-of-numbers#answer_121526

编辑：Matt J 2014-1-20

在 MATLAB Online 中打开

kdata_combined = cell2mat(kdata)

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Eduardo 2014-1-20

编辑：Eduardo 2014-1-20

matlab.mat

I usually have 1 cell array with 5, 10 or any number of cell arrays in it.

Every one of them are like 4000x3 or 4000x2. But they're all the same size. My example was wrong, sorry about that.

I attached a real .mat file with one cell array.

Matt J 2014-1-21

在 MATLAB Online 中打开

Just do

kdata_combined=[kdata{:}];

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Answer 2

John Thompson 2014-1-20

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https://ww2.mathworks.cn/matlabcentral/answers/113029-combine-a-cell-array-of-cell-arrays-to-a-cell-array-of-numbers#answer_121545

编辑：John Thompson 2014-1-20

在 MATLAB Online 中打开

   % Initialize fake data
   cellA = cell(10,1);
   for i = 1:10
       cellA{i} =  num2cell(round(rand(10,1)*10));
   end
   % RUN THIS to extract and realign nested cell arrays
   cac = cell2mat(cellfun(@(x) cell2mat(x)' , cellA, 'UniformOutput', false));

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Answer 3

per isakson 2014-1-21

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/113029-combine-a-cell-array-of-cell-arrays-to-a-cell-array-of-numbers#answer_121698

编辑：per isakson 2014-1-21

在 MATLAB Online 中打开

You have a cell array of cell arrays of strings. Your strings consist of one and in some cases two characters. The solution, which I proposed, assumed that all strings are of the same length. Since they are not you get the error

    Error using cat
    Dimensions of matrices being concatenated are not consistent.
    Error in cell2mat (line 84)
                m{n} = cat(1,c{:,n});

.

I missed the word "number" in the topic title.

Does this do the job?

    cac = cat( 2, kdata{:} );
    num = str2double( cac );
    cac_num = num2cell( num );

or this

kdata_combined = cat( 2, kdata{:} );

both assume that kdata is .< 1 xn cell>

.

[Later]

and when kdata is .< m xn cell>

    cc = repmat( kdata, 400, 1 ); 
    tic
    nrows = size( cc, 1 );
    cac = cell( nrows, 1 );
    for jj = 1 : nrows
        cac{ jj } = cat( 2, cc{ jj, : } );
    end
    kdata_combined = cat( 1, cac{:} );
    toc
    whos('kdata_combined')

returns

    Elapsed time is 0.108852 seconds.
      Name                     Size                Bytes  Class    Attributes
      kdata_combined      114800x24            314099200  cell