title: What does this 'for m,n in matches'?
body: <p>I need to know specifically what the line <code>for m, n in matches</code> does to be able to implement it in C. <code>matches</code> is a matrix, but what values does <code>m</code> and <code>n</code> take and how do they move?</p>
  
  <p>This is python code...</p>
  
  <pre><code>for m, n in matches:
      if m.distance &lt; 0.75*n.distance:
          good.append([m])
  </code></pre>
  
  <p>NOTE In C++ <code>matches</code> is a <code>std::vector&lt;DMatch&gt;</code> and is an OpenCV program.</p>
  
  <p>Thanks! </p>