C-order reshape of multi-dimensional array in matlab
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Hello,
I have a question regarding reshape in matlab, it seems that matlab reshapes N-dimensional array according to Fortran-order, however, I would like a C-order reshape, that is a line-wise reshape.
Suppose now there is a matrix M with 4 rows and 4 columns as follows:
M = [1 2 3 4
5 6 7 8
9 10 11 12
13 14 15 16]
Then M is going to be reshaped to a 3D array with dimension (2,2,4) shown in the picture below. Does anyone know how to do this in a generalized way (suitable for even higher dimension)?
Thanks!
![reshape_problem_2.jpg](https://www.mathworks.com/matlabcentral/answers/uploaded_files/208011/reshape_problem_2.jpeg)
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Accepted Answer
Jan
on 10 Mar 2019
Edited: Jan
on 10 Mar 2019
Reshaping in line-wise order is not meaningful, because reshaping means to keep the order of elements in the memory and the order is defined columnwise in Matlab. But you can simply change the order by permute:
x = rand(2,3,4);
y = permute(x, [2, 1, 3:ndims(x)]);
result = reshape(y, [whateverYouWant])
7 Comments
Steven Lord
on 7 Sep 2022
That's the mapping between the dimensions of your original array and the dimensions of the result.
A = reshape(1:24, [4 3 2]);
szA = size(A)
p = [2 1 3];
B = permute(A, p);
szB = size(B)
A is size 4 in its first dimension. Because the first element of p is 2, B is size 4 in its 2nd dimension.
A is size 3 in its second dimension. Because the second element of p is 1, B is size 3 in its 1st dimension.
I was very careful to distinguish first and second from 1st and 2nd in those descriptions.
Stephen23
on 7 Sep 2022
"Therefore I do not understand, why my code "fails the mission"."
I accepted your answer, Jan, because it is clear that permuting the first two dimensions is the general solution.
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