mat2cell sizes

Question

hmalissa 2017-11-10

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/366185-mat2cell-sizes

评论： Walter Roberson 2017-11-10

Within a function, I convert a cell array C_in to a numeric array A_in:

A_in = cell2mat(C_in);

I then perform calculations on A_in that will result in A_out with the same size as A_in. In the end, I need to convert the numeric array A_out to a cell array C_out, with the sizes of C_out being exactly the same as C_in. I know that mat2cell is used for this, but I was wondering if there is a straight-forward way to have mat2cell figure out the row and column distances automatically based on C_in. C_in is expected to have a size of {[1, n1], [1, n2], [1, n3], ...} or {[n1, 1], [n2, 1], [n3, 1], ...}, and my function should produce a C_out with identical dimensions in both cases.

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Answer 1

Walter Roberson 2017-11-10

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/366185-mat2cell-sizes#answer_290325

在 MATLAB Online 中打开

cellsizes = cellfun(@size, C_in);
C_r = cellfun(@(M) M(1), cellsizes);
C_c = cellfun(@(M) M(2), cellsizes);
mat2cell(A_out, C_r, C_c)

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hmalissa 2017-11-10

在 MATLAB Online 中打开

The problem with the example above (which is very close to my application, since I'm dealing with C_in with similar shape) is that C_r is [1 1], but mat2cell requires '1' instead. I found that 'unique' produces the correct output:

C_out = mat2cell(A_out, unique(C_r), unique(C_c));

Thanks for your help! I'm just surprised that there isn't a built-in implementation of this.

Walter Roberson 2017-11-10

在 MATLAB Online 中打开

cellsizes = cellfun(@size, C_in, 'Uniform', 0);
if size(A_in,2) == 1
  C_r = cellfun(@(M) M(1), cellsizes);
  C_c = 1;
else
  C_r = 1;
  C_c = cellfun(@(M) M(2), cellsizes);
end
C_out = mat2cell(A_out, C_r, C_c);