title: Index of Instance in Instances
body: <p>I use the Weka library for K-Means and I decided to change distance function between <code>Instance i1</code> and <code>Instance i2</code>, which is contained in dataset <code>Instance data</code>. How do I get the index of <code>i1</code> and <code>i2</code> in <code>data</code>?</p>
  
  <p><a href="http://weka.sourceforge.net/doc.dev/weka/core/Instance.html" rel="nofollow">Weka API</a> here. I can't find it.</p>