title: How do I keep the column names when I convert a pandas df to np array?
body: <p>I need to convert a pandas df to np array, but I lose the column names in the process. I have read and googled for a while now and I'm stuck. </p>
  
  <p>My df looks like this:</p>
  
  <pre><code>mont_data.tail()
  Out[114]: 
  Index        MOEX.ME     ^GSPC      ^MXX     ^N225    ^OSEAX
  Date                                                        
  2016-05-31  0.001482 -0.004077  0.002506 -0.000005  0.033240
  2016-06-30  0.074850  0.008136 -0.002262 -0.029029  0.002518
  2016-07-31  0.025882  0.030147  0.024242  0.007169  0.032473
  2016-08-31  0.059069  0.014333  0.025050  0.025243 -0.008767
  2016-09-30  0.035201 -0.009029 -0.016499 -0.039833 -0.003520
  </code></pre>
  
  <p>I then do: </p>
  
  <pre><code>mont_arr = mont_data.as_matrix(columns=[mont_data.columns[0:5]])
  </code></pre>
  
  <p>or: </p>
  
  <pre><code>mont_arr = mont_data.as_matrix(columns=[mont_data.columns[0:]])
  </code></pre>
  
  <p>Both result in a np array without column headers. Any idea how to solve this? </p>
  
  <p><sub>Using latest version of mentioned packages with Python 3.5
  </sub></p>