converting a cell array of doubles in a matrix

Question

Haneya Qureshi 2018-6-19

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https://ww2.mathworks.cn/matlabcentral/answers/406390-converting-a-cell-array-of-doubles-in-a-matrix

评论： OCDER 2018-6-19

I have a variable A which looks like this:

1×2 cell array
    {1×9 double}    {1×9 double}

I want to convert it to a matrix, i.e, the first row of matrix should be what's inside the A{1} and second row of matrix should be what's inside A{2}. A is a cell, but A{1} and A{2} are doubles. How can i do this?

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Stephen23 2018-6-19

在 MATLAB Online 中打开

vertcat(A{:})

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Answer 1

Ameer Hamza 2018-6-19

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https://ww2.mathworks.cn/matlabcentral/answers/406390-converting-a-cell-array-of-doubles-in-a-matrix#answer_325307

在 MATLAB Online 中打开

A{1} = rand(1,9);
A{2} = rand(1,9);
cell2mat(A')
A =
1×2 cell array
  {1×9 double}    {1×9 double}
ans =
Columns 1 through 7
  0.0844    0.3998    0.2599    0.8001    0.4314    0.9106    0.1818
  0.1361    0.8693    0.5797    0.5499    0.1450    0.8530    0.6221
Columns 8 through 9
    0.2638    0.1455
    0.3510    0.5132

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Haneya Qureshi 2018-6-19

Thank you so much! This works perfectly!

Ameer Hamza 2018-6-19

You are welcome.

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Answer 2

OCDER 2018-6-19

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https://ww2.mathworks.cn/matlabcentral/answers/406390-converting-a-cell-array-of-doubles-in-a-matrix#answer_325310

在 MATLAB Online 中打开

A = {rand(1,10000), rand(1,10000)};
B = vertcat(A{:});

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OCDER 2018-6-19

在 MATLAB Online 中打开

cell2mat is certainly the right function for converting cell arrays to matrices while preserving the MxN dimension of the cell array. However, vertcat is a built-in function (meaning super optimized) and will run ~2x faster for your case.

A = {rand(1,10000), rand(1,10000)};
t1 = timeit(@() vertcat(A{:}), 1);
t2 = timeit(@() cell2mat(A), 1);
fprintf('cell2mat(A'') time is %0.2f times slower than vertcat(A{:})\n', t2/t1);

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