title: calculating cumulative geometric mean
body: <p>trying to create a function that will solve for the cumulative geometric mean for a vector or for columns of an array.  </p>
  
  <p>I can solve the geometric mean of the entire vector/column..simply need to do the following: </p>
  
  <pre><code>from scipy import stats
  GM=stats.gmean(X)
  print(GM)
  </code></pre>
  
  <p>When solving the cumulative arithmetic means, I can simply run pd.expanding_mean(x) to get the cumulative mean.</p>
  
  <p>Is there a function I can run which would give me the same result for the geometric mean?</p>