How can I use randperm.m to convert one matrix to another?

Hi,

I want to take an m x n matrix called A, generate a random permutation of each row, and then place that random permutation into a new matrix called B. I want to use randperm to do this and I want the code to do the entire matrix so that I end up with a new m x n matrix where each row has been effectively randomly reordered. So far, I have only be able to generate the first row of matrix B using code like this:

matrixB = matrixA( randperm(length(matrixX)) );

What is the best way to write the code so that it does ALL of the rows?

Answer 1

[Azzi Abdelmalek]

A=magic(6) % example
[n,m]=size(A)
B=cell2mat(arrayfun(@(x) A(x,randperm(m)),(1:n)','un',0))

Answer 2

[Sean de Wolski]

SO stick it in a for-loop, this will be the best way to do this unless you really want to be fancy, in which case I think this will still be the best way to do this:

sz = size(matrix(A));
matrixB = zeros(sz);
for ii = 1:sz(1)
  matrixB(ii,:) = matrixA(ii,randperm(sz(2)));
end

Answer 3

[Matt Fig]

% Say we are given this:
A = randi(100,4,8);  
% Now the method:
[m,n] = size(A);
B = bsxfun(@(x,y) A(y,randperm(x)).',n*ones(n,1),1:m).'