title: Plotting dendrogram in Scipy error for large dataset
body: <p>I am using Scipy for hierarchial clustering. I do manage to get flat clusters on a threshold  using fcluster. But I need to visualize the dendrogram formed. When I use the dendrogram method, it works fine for 5-6k user vectors. But my dataser consists of 16k user vectors. When I run it for 16k users dendrogram function throws the following error:</p>
  
  <pre><code>File "/home/enthought/lib/python2.7/site-packages/scipy/cluster/hierarchy.py", line 2333, in _dendrogram_calculate_info
  leaf_label_func, i, labels)
  File "/home/enthought/lib/python2.7/site-packages/scipy/cluster/hierarchy.py", line 2205, in _append_singleton_leaf_node
  ivl.append(str(int(i)))
  RuntimeError: maximum recursion depth exceeded while getting the str of an object
  </code></pre>
  
  <p>Any ideas on visualizing dendrogram for larger dataser?</p>