MATLAB: Matrix Elements Re-ordering

matrixmatrix manipulation

If I have a matrix A that is:

A = [1, 2; 3, 4; 5, 6;7, 8]

How can I reorder it so that it becomes,

A = [1,3;5,7;2,4;6,8]

i.e. basically re.arranging the matrix elements in a row-by-row basis (the first 2 elements of column 1 become the 2 elements in row 1; the second 2 elements of column 1 become the 2 elements in row 2, etc).

Thank you for your help in advance!

Best Answer

 >> B = reshape( A, 2, [] ).'
 B =
     1     3
     5     7
     2     4
     6     8

Related Solutions

MATLAB: Sparse matrix re-ordering

I tried to generalize your code as follows.

A = [-1 -2  0 4  0  0  0  1  0 0;
      3  2  0 0  0  0 -4  0  0 3;
      0  0  5 7 -6  0  3  4  0 1;
      2  0  1 1 -1  0  0  0  0 0;
      0  0  2 4 -1  8  6  0  0 3;
      0  0  0 0  2 -2  4  0  0 0;
      0  3 -3 0  1  9  5 -3 -6 0;
     -1  0  2 0  0  0  4 -5  0 0;
      0  0  0 0  0  0 -1  0  2 0;
      0  2  2 0  5  0  0  0  0 7];
% Store the graph info for the original array, in the first element of a
% new cell array
G{1} = graph(A,'upper');
N = length(A);
% Initialize the output as an empty vector that we will append to
output = nan(N,1);
original = 1:N;
for i = 1:N
    % Find the degree list (and store for later inspection)
    deg{i}     = degree(simplify(G{i}));
    % Sort the degree list
    [deg{i},k] = sort(deg{i},'ascend');
    % Remove lowest degree from graph, and store new graph
    G{i+1}     = rmnode(G{i},k(1));
    % Add lowest degree position to output
    output(i)  = original(k(1));
    % Delete the lowest degree position from the original list
    original(k(1)) = [];
end

However, I don't get the same final output as you state. (The first few match with yours.)

I can't determine whose is incorrect. I tried to comment my code very carefully, so that you could follow what I did, and find a coding mistake.

MATLAB: Find missing element between two matrix

>> A = [1,2;3,6;3,5;1,4;4,6;2,7;1,6;6,5;2,3;6,7;3,4];
>> B = [1,2;1,6;2,3;3,4;4,6];
>> R = setdiff(A,B,'rows')
R =
   1   4
   2   7
   3   5
   3   6
   6   5
   6   7

To get the same order, use the 'stable' option or this:

>> [~,X] = setdiff(A,B,'rows');
>> X = sort(X);
>> R = A(X,:)
R =
   3   6
   3   5
   1   4
   2   7
   6   5
   6   7

Best Answer

Related Solutions

MATLAB: Sparse matrix re-ordering

MATLAB: Find missing element between two matrix

Related Question