title: Save pandas dataframe with numpy arrays column
body: <p>Let us consider the following pandas dataframe:</p>
  
  <pre><code>df = pd.DataFrame([[1,np.array([6,7])],[4,np.array([8,9])]], columns = {'A','B'})
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/EzXPm.png" rel="noreferrer"><img src="https://i.stack.imgur.com/EzXPm.png" alt="enter image description here"></a></p>
  
  <p>where the <strong>B</strong> column is composed by two numpy arrays.</p>
  
  <p>If we save the dataframe and the load it again, the numpy array is converted into a string.</p>
  
  <pre><code>df.to_csv('test.csv', index = False)
  df.read_csv('test.csv')
  </code></pre>
  
  <p>Is there any simple way of solve this problem? Here is the output of the loaded dataframe.</p>
  
  <p><a href="https://i.stack.imgur.com/N4c45.png" rel="noreferrer"><img src="https://i.stack.imgur.com/N4c45.png" alt="enter image description here"></a></p>