Convert a vector into a matrix (row wise)

Let us assume vector A as follows:

A = [1 2 3 4; 5 6 7 8; 9 10 11 12];

I create two vectors (row wise) from this matrix as follows:

CP = randi([1 numel(A)]-1);
B = transpose(A);
C = B(1:CP);
D = B(CP+1:end);

Now, when I use reshpe function to construct a matrix as the same as A, the result is something else.

reshape([C D], 3, 4)

It seems that I need to make reshape to construct the matrix in row wise. Could you please help me?

[James Tursa]

Can you explain what you want to get as output? I.e., show us the actual numeric output you want.

Answer 1

[Tommy]

From the reshape() docs, for the syntax

B = reshape(A,sz)

"The elements in B preserve their columnwise ordering from A."

If you want to "reshape" a vector so that the output matrix is filled along the rows first, you could reverse the requested dimensions in your call to reshape() and then transpose the result:

A2 = reshape([C D], 4, 3)';

I believe this could be generalized to any number of dimensions with a combination of reshape() and permute().