How to select two matrices randomly from a set of N matrices and then randomly select a few rows from first selected matrix and then exchange with corresponding rows of other selected matrix.

For example we have 10 matrices A,B,C,D,E,F,G,h,I,J and we select randomly two matrices C and H. And then Randomly select any two rows from C and exchange with corresponding rows of H.

Answer 1

[Thorsten]

Q = cat(3,A,B,C,D,E,F,G,H,I,J);
kk = randperm(size(Q, 3), 2); % select 2 matrices from Q
ii = randperm(size(Q, 1), 2); % select 2 rows
Q(ii, :, kk) = Q(ii, :, fliplr(kk));

Answer 2

[Andrei Bobrov]

For the case where the matrices have the same size:

Q = cat(3,A,B,C,D,E,F,G,H,I,J);
ii = [3,8] % C and H
n = size(Q,1);
z = 1:n;
jj = z(randperm(n,2));
M = Q(:,:,ii);
M(jj,:,:) = M(jj,:,end:-1:1);
Q(:,:,ii) = M;

[Thorsten]

 z = 1:n;
 jj = z(randperm(n,2));

is the same as

jj = randperm(n,2);

And you don't need the temporarily variable M but can work directly on Q.

[Andrei Bobrov]

Thanks Torsten! I totally agree with you.