How to get random values from a matrix

There is a matrix A (size:12x1000)

How can I select 5 random entries out of 1000( from a matrix of size 12x1000), with each randomly selected value contains all the 12 rows from the original matrix. And store it into another matrix of size 12x5.

Can anyone help me with the code.

Answer 1

[Ameer Hamza]

You can use randperm() in a for-loop

M = rand(12, 1000);

rand_elements = zeros(12, 5);
for i = 1:12
    idx = randperm(1000, 5);
    rand_elements(i,:) = M(i, idx);
end

Answer 2

[Stephan]

% Test data to play with
A = rand(12,1000);

% Preallocate
idx = zeros(size(A,1),5);

% 5 unique random indices for every row: 
for k = 1:size(A,1)
    idx(k,:) = randperm(size(A,2),5);
end

% result
B = A(idx)

Answer 3

[Bruno Luong]

rcols = randperm(size(A,2),5);
B = A(:,rcols)

[Stephan]

I think same indexes for different rows are allowed - arent they?

[Bruno Luong]

I just interpret the question like this. I don't know if it's what OP wants or not.