How can I sample n elements from each column of a matrix?

I have this matrix:

A =

1 5 9 13 17

2 6 10 14 18

3 7 11 15 19

4 8 12 16 20

I want to sample n elments with replacement from each column. For instance, if n=2, I would like to get something like:

B =

2 8 10 14 20

4 8 9 15 17

I tried datasample, but it samples entire rows. Is there an efficient way to do this without using a for loop?

[KSSV]

YOu want to select two elements from each column randomly?

Answer 1

[David Hill]

B=A(randi(size(A,1),2,size(A,2))+(0:size(A,2)-1)*size(A,1));

[Raphael]

That is exactly what I wanted!

Very clever, David.

Thank you!

Answer 2

[Birdman]

Following approach can be used(using for loop):

n=2;
for i=1:size(A,2)
    y(:,i)=randsample(A(:,i),n);
end
y

Answer 3

[Stephen23]

>> X = sub2ind([4,5],randi(4,2,5),[1:5;1:5]);
>> B = A(X)
B =
    3    8    9   13   20
    3    7   10   15   20