MATLAB: Select randomly “N” rows of a matrix

matrixrandomlyrows

how i can select randomly "N" rows of a matrix? for example

M =

     [ a12, a12]
     [ a21, a22]
     [ a31, a32]
     [ a41, a42]

For N=2

B =

     [ a12, a12] 
     [ a31, a32] 
     [ a21, a22]

try:

N=2; % no. of rows needed
M=rand(5)  % generate a 5x5 matrix random
c=randperm(length(M),N)  
B=M(c,:)  % output matrix

msize = numel(YourMatrix);
idx = randperm(msize);
YourMatrix(idx(1:x))

If you have a fairly new version of MATLAB, you can instead use

msize = numel(YourMatrix);
YourMatrix(randperm(msize, x))

A = rand(1,3) ;
B = rand(1,3) ;
C = [A' B'] ;