title: kmeans clustering : how to access cluster datapoints
body: <p>Here is an implementation of kmeans algorithm that I put together from the kmeans scikit documentation and a blog post discussing kmeans : </p>
  
  <pre><code>#http://scikit-learn.org/stable/modules/generated/sklearn.cluster.KMeans.html
  #http://fromdatawithlove.thegovans.us/2013/05/clustering-using-scikit-learn.html
  
  from sklearn.cluster import KMeans
  import numpy as np
  from matplotlib import pyplot
  
  X = np.array([[10, 2 , 9], [1, 4 , 3], [1, 0 , 3],
                 [4, 2 , 1], [4, 4 , 7], [4, 0 , 5], [4, 6 , 3],[4, 1 , 7],[5, 2 , 3],[6, 3 , 3],[7, 4 , 13]])
  kmeans = KMeans(n_clusters=3, random_state=0).fit(X)
  
  k = 3
  kmeans.fit(X)
  
  labels = kmeans.labels_
  centroids = kmeans.cluster_centers_
  
  for i in range(k):
      # select only data observations with cluster label == i
      ds = X[np.where(labels==i)]
      # plot the data observations
      pyplot.plot(ds[:,0],ds[:,1],'o')
      # plot the centroids
      lines = pyplot.plot(centroids[i,0],centroids[i,1],'kx')
      # make the centroid x's bigger
      pyplot.setp(lines,ms=15.0)
      pyplot.setp(lines,mew=2.0)
  pyplot.show()
  
  print(kmeans.cluster_centers_.squeeze())
  </code></pre>
  
  <p>How to print / access the data points of each of the k clusters . </p>
  
  <pre><code>if k = 3 : 
  cluster 1 : [10, 2 , 9], [1, 4 , 3], [1, 0 , 3]                  
  cluster 2 : [4, 0 , 5], [4, 6 , 3],[4, 1 , 7],[5, 2 , 3],[6, 3 , 3],[7, 4 , 13]
  cluster 3 : [4, 2 , 1], [4, 4 , 7]
  </code></pre>
  
  <p>Reading <a href="http://scikit-learn.org/stable/modules/generated/sklearn.cluster.KMeans.html" rel="nofollow noreferrer">http://scikit-learn.org/stable/modules/generated/sklearn.cluster.KMeans.html</a> there is not a attribute or method on the <code>kmeans</code> object for this ?</p>
  
  <p>Update  : </p>
  
  <p><code>kmeans.labels_</code> returns <code>array([1, 0, 2, 0, 2, 2, 0, 2, 0, 0, 1], dtype=int32)</code></p>
  
  <p>But how does this show the data points in each of the 3 clusters ? </p>