Convert 3D cell array (with 3D vector in each cell) into a single matrix

Question

Hayao 2018-4-13

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/394580-convert-3d-cell-array-with-3d-vector-in-each-cell-into-a-single-matrix

评论： Ameer Hamza 2018-5-2

I have a n-by-n-by-n cell array, where each cell contains a vector of 3D coordinate. I want to convert this 3D cell array into a single n^3-by-3 2D matrix.

For example, suppose I have 3x3x3 cell array with each cell containing a 3D vector (with coordinate [x y z]). I want to make a matrix that looks like this:

[x1 y1 z1]

[x2 y2 z2]

...

[x27 y27 z27]

Of course I will not be able to use cell2mat command for this. So my intuition was to concatenate using for loop. Let's say C is the 3x3x3 cell array containing 3D vectors in each cell:

M = zeros(0,3)
for c = 1:3
  for b = 1:3
    for a = 1:3
      M = cat(1,M,C(a,b,c))
    end
  end
end

Is there a more straightforward way to do this? Because this seems like a inefficient method to use, especially when I am planning to extend it to n-by-n-by-n 3D cell array. Or is this the only way to do this?

Note: Searching the MATLAB answers only yielded results that were specialized to each of the question and was not applicable for my situation.

Thank you