title: python numpy - convert Timestamps to datetime
body: <p>I have a np array such as follow:</p>
  
  <pre><code>example = np.array([[Timestamp('2005-03-06 17:00:00'), 1225.75, 1226.25, 1225.0, 1225.5,
          1668.0],
         [Timestamp('2005-03-06 17:30:00'), 1225.75, 1227.5, 1225.75, 1227.0,
          1603.0],
         [Timestamp('2005-03-06 18:00:00'), 1227.0, 1227.5, 1226.75, 1227.25,
          590.0]], dtype=object)
  </code></pre>
  
  <p>The first column is a Timestamp type value.
  How do i convert those values to datetime?
  I know there are few similar questions on the topic, but i couldnt manage to form a clear understanding of it and figure out a clean neat solution based on them.</p>
  
  <p>I can convert the timestamp of a single value with <code>example[0,0].to_datetime()</code> but how to do it on all the Timestamps at once? ideally something like <code>example[:,0].</code>...</p>