MATLAB：结构的二维数组（包含向量）到3-D数组？

Question

I have a 2-dimensional array of structs 'cell' which each contain a number of vectors:

cell(1,1).U = [1 2 3];
cell(1,2).U = [4 5 6];
cell(2,1).U = [7 8 9];
cell(2,2).U = [0 1 2];

I would like to extract the data into a 3-D array A(i,j,k).

Using cell-style extraction returns a 1x3 cell, the contents of which are

>> {cell.U}
ans = {[cell(1,1).U]   [cell(1,2).U]   [cell(2,1).U]   [cell(2,2).U]}

And thus, converting this to a matrix using cell2mat(), as in:

cell2mat(ans)

Returns a 3x4 array.

Ideally, I would like a 2x2x3 array so that the indices i and j are preserved. Is there any way (short of looping) to accomplish this?

Answer 1

Use CAT and RESHAPE . Also, don't call your variable cell , since that's a built-in function.

>> c(1,1).U = [1 2 3];
c(1,2).U = [4 5 6];
c(2,1).U = [7 8 9];
c(2,2).U = [0 1 2];


>> out = cat(1,c.U)
>> out = reshape(out,2,2,3)
out(:,:,1) =
     1     4
     7     0
out(:,:,2) =
     2     5
     8     1
out(:,:,3) =
     3     6
     9     2