title: plot the centroid values over the existing plot using matplotlib
body: <p>How to plot the centroid values as computed below over the plot?    </p>
  
  <pre><code>import numpy as np, matplotlib.pyplot as plt
  from scipy.cluster.vq import kmeans, vq
  
  data = np.array(np.random.rand(100))
  
  plt.plot(data, 'ob')
  
  
  centroids, variances= kmeans(data,3,10)
  indices, distances= vq(data,centroids)
  
  print (centroids)
  [ 0.82847854  0.49085422  0.18256191]
  
  plt.show()
  </code></pre>