title: calculate cluster centroid using kmeans
body: <p>I want to calculate the centroid vector for a cluster with scikit-learn:</p>
  <pre><code>from sklearn.cluster import KMeans
  import numpy as np
  
  kmeans = KMeans(n_clusters=1, random_state=0).fit(X)
  </code></pre>
  <p>If I set <code>n_cluster=1</code>, does this mean I calculate the mean of X?</p>
  <p>For example, if there are three data points in X, and each data point has a 4d vector, <code>X=[[1,2,3,4],[2,3,4,5],[6,7,8,9]]</code>, so after I used kmeans to calculate the centroid vector, it will be <code>centroid_vect = [3,4,5,6]</code>?</p>