randperm

How can I use randperm for a nx2 matrix?

[Dr. Seis]

"randperm" only takes 1 scalar input argument. Can you give a sample of an input nx2 matrix AND what you would expect the output to be?

Answer 1

[Jonathan]

If you want to randomly permute the rows, do something like the following.

n = 5;
A = reshape(1:2*n, n, 2)
B = A(randperm(n), :)

If you want to randomly permute all elements, do something like this instead.

C = reshape(A(randperm(2*n)), n, 2)

[Jonathan]

@Miriam, to permute the columns separately do this.

D = A;

D(:,1) = D(randperm(n),1);

D(:,2) = D(randperm(n),2);

Answer 2

[Miriam]

I see, hmm.. actually I wanted to permute the two columns seperately, but I guess this will not work with randperm. But the suggestions were very helpful anyway! Thanks!

Answer 3

[Jan]

You can use FEX: Shuffle:

A   = rand(100, 2);
Dim = 1;
B   = Shuffle(A, Dim);