title: Get a new df with the mean values of other dfs
body: <p>I have 1 list composed of unknown number  of dfs:</p>
  
  <p>The dfs have same dimensions with same column names and same column values in the same order: </p>
  
  <pre><code>df1=pd.DataFrame(data=np.transpose([[1,2,3,4],[2,4,6,8]]),index=['A','B','C','D'],columns=['x','y'])
  df2=pd.DataFrame(data=np.transpose([[3,3,3,3],[4,4,4,4]]),index=['A','B','C','D'],columns=['x','y'])
  </code></pre>
  
  <p>I would like to group the values of the n dfs into a new df with the values being the mean of the values of the n dfs</p>
  
  <p>The ouput </p>
  
  <pre><code>df2=pd.DataFrame(data=np.transpose([[2,2.5,3,3.5],[3,4,5,6]]),index=['A','B','C','D'],columns=['x','y'])
  </code></pre>