title: "AttributeError: 'matrix' object has no attribute 'isocalendar'" in numpy python
body: <p>I have a numpy matrix as the following:</p>
  
  <pre><code>dates = np.matrix([['09/01/70'], ['10/01/70'], ['11/01/70']])
  </code></pre>
  
  <p>And I want to convert this matrix to a matrix which involves week numbers instead of the dates.</p>
  
  <p>Thanks to "isocalendar()" function in python, you can find the week number of the date. </p>
  
  <p>But when I used the function as the following;</p>
  
  <pre><code>weeks = dates.isocalendar()[1],
  </code></pre>
  
  <p>I get this error: </p>
  
  <pre><code>AttributeError: 'matrix' object has no attribute 'isocalendar'
  </code></pre>
  
  <p>What is the right way of converting the date matrix to datenumber matrix in numpy python?</p>