title: How to select rows in a table whose row.names match any element from a character vector?
body: <p>I have a big table (over 20,000 rows) containing a couple of columns saved in a matrix <code>x</code>. I also have character vector <code>z</code> containing a couple of thousand of the row names used in the big table. How can I extract all the rows from the matrix <code>x</code> where the row name matches one of elements in the vector <code>z</code>?</p>