How do I extract subscript numbers from a matrix element?

Question

0 个投票

Hi, I have a sparse matrix V as you can see.

What I want to do is to extract the rows' subscript numbers and put into a vector matrix X. Example: X = (108, 120, 127, n, ...).

And do the same to col's subscript numbers, putting it into Y = (1, 1, 1, 2, 2, n, ...)

Than, simply plot it using plot(X, Y);

Thank you in advance!

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

Answer 1

José-Luis 2014-6-10

编辑：José-Luis 2014-6-10

0 个投票

 [row,col]  = find(V);
 plot(row,col,'r+');

Victor Noronha 2014-6-10

Thank you, worked great, but it seems to be rotated 90 degrees counterclockwise.

Answer 2

Jos (10584) 2014-6-10

0 个投票

    help find  
    V = sparse(rand(5)>.5)
    [x,y] = find(V)
    plot(x,y,'b.')

and take a look at

help spy
spy