title: How to find offset diagonal of a matrix?
body: <p>Is there an easy way to extract a vector of an 'offset' and 'reverse' "diagonal" (the x's) of a matrix in R?</p>
  
  <pre><code>      [,1] [,2] [,3] [,4] [,5]
  [1,]    x    0    0    0    0
  [2,]    0    0    0    0    x
  [3,]    0    0    0    x    0
  [4,]    0    0    x    0    0
  [5,]    0    x    0    0    0
  </code></pre>
  
  <p>I tried <code>diag()</code> but it does'nt seem to take any options..</p>