MATLAB: Retrieving a random element from each row in a matrix

for loopsMATLAB

hi everyone
I have a 20 by 10 matrix. I am running the following code to retrieve a random element from each row of the matrix. In this case, I need to create a 20 by 1 matrix at the end. I have written the following code but it does give me a shuffle of the first column alone. 
sz=size(R,1);
B=zeros(sz,1);
i=1:20
% for n=1:100
for j=1
    for i=1:20
        for row=1:20
            M(i,j)=randi(length(R),20,1);
            B(i,j)=R(M(i,j));
        end
    end
end
% end

Best Answer

It is likely easier to use the sub2ind funciton to create linear indices into ‘R’ from a defined list of random column subscripts: 
R=randi(1000,20,10);
idx = sub2ind(size(R), (1:size(R,1))', randi(size(R,2),size(R,1),1));
B = R(idx)
The second argument defines the row indices and the third defines the random column indices.
See if that does what you want.
Related Question