title: how to generate a graph/diagram like Google Analytics's Visitor Flow?
body: <p>I am trying to generate a diagram similar to that presented by the recent Google Analytics "Visitor Flow". These are also known as <a href="http://en.wikipedia.org/wiki/Alluvial_diagram" rel="noreferrer" title="similar to this">Alluvial diagrams</a>. </p>
  
  <p>I can use a web or non-web based solution, as long as I can run it myself. </p>
  
  <p>The data I want to visualize is the following:</p>
  
  <ul>
  <li>at time t1, I have x1 units, divided into n1 parts</li>
  <li>at time t2, the n1 parts split (or merged) into n2 parts, with x2 units
  
  <ul>
  <li>i want to show where the splits/merges are taking place. </li>
  </ul></li>
  </ul>
  
  <p>My data is currently represented with a DiGraph in <a href="http://networkx.lanl.gov/" rel="noreferrer" title="networkx">NetworkX</a>, but this may be irrelevant, since I can output my data in any format required.</p>
  
  <p><img src="https://i.stack.imgur.com/S0bzl.png" alt="Similar to the diagram below"></p>