2 0.33541124925
3 0.205739155166
4 0.160090671224
Traceback (most recent call last):
  File "/Users/aleserjavec/devel/orange/Orange/testing/regression/xtest_one.py", line 115, in <module>
    execfile(t__name)
  File "modules_kmeans-silhouette.py", line 12, in <module>
    orngClustering.plot_silhouette(km, "kmeans-silhouette.png")
  File "/Users/aleserjavec/devel/orange/Orange/clustering/kmeans.py", line 276, in plot_silhouette
    import matplotlib.pyplot as plt
ImportError: No module named matplotlib.pyplot
