# Convert a vector into a matrix (row wise)

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Amirhossein Moosavi on 2 Jul 2020
Edited: Tommy on 2 Jul 2020
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 on 2 Jul 2020
Can you explain what you want to get as output? I.e., show us the actual numeric output you want.

Tommy on 2 Jul 2020
Edited: Tommy on 2 Jul 2020
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().