Vector Manipulation into a matrix?

I have a vector, A, of dimensions 21-by-1. How would I be able to manipulate this matrix such that:

A = [a;b;c;d;e;f;g;h;i;...]

Becomes a 3-by-7 matrix, B:

B = [c,b,a;f,e,d;i,h,g,...]

Any help would be much appreciated! Thanks.

Answer 1

[Sriram Tadavarty]

Hi Daniel,

This can be solved by first using the reshape function and then performing the circular shift operation.

% Suppose the vector is a - of length 21
a = rand(21,1); % random column vector 21-by-1

% Now use the reshape operation to the desired size
aReshape = reshape(a,3,7); % Size is 3-by-7

% Store the first row in a variable
temp = aReshape(1,:);

% Replace the first row with the third row
aReshape(1,:) = aReshape(3,:);

% Replace the third row with the first row
aReshape(3,:) = temp;

out = aReshape;

The documentation link for the reshape function is

https://www.mathworks.com/help/matlab/ref/reshape.html

Hope this helps.

Regards,

Sriram

[Daniel Tanner]

Thank you Sriram, very informative answer and much more understandable now!

Answer 2

[Fangjun Jiang]

A=(1:21)';
temp1=reshape(A,3,[]);
temp2=temp1';
B=fliplr(temp2)

[Daniel Tanner]

Thank you!