split long 2D matrix into the third dimension

Question

Say I have the following matrix: ``` A = randi(10, [6 3]) 7 10 3 5 5 7 10 5 1 6 5 10 4 9 1 4 10 1 ``` And I would like to extract each 2 rows and put them into the third dimension, so the result would be like: ``` B(:,:,1) = 7 10 3 5 5 7 B(:,:,2) = 10 5 1 6 5 10 B(:,:,3) = 4 9 1 4 10 1 ``` I can obviously do this with a for loop, just wondering how to do it more elegantly as one-liner using permute/reshape/.. (note matrix size and step must be parameters) ``` % params step = 5; r = 15; c = 3; % data A = randi(10, [r c]); B = zeros(step, c, r/step); % assuming step evenly divides r % fill counter = 1; for i=1:step:r B(:,:,counter) = A(i:i+step-1, :); counter = counter + 1; end ```

Accepted Answer

Here's a one-line solution using `reshape` and `permute`:

```
C = 3;          % Number of columns
R = 6;          % Number of rows
newR = 2;       % New number of rows
A = randi(10, [R C]);  % 6-by-3 array of random integers
B = permute(reshape(A.', [C newR R/newR]), [2 1 3]);
```

This of course requires that `newR` divides evenly into `R`.

split long 2D matrix into the third dimension

Solution

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