title: Convert numpy.datetime64 to string object in python
body: <p>I am having trouble converting a python <code>datetime64</code> object into a string. For example:</p>
  
  <pre><code>t = numpy.datetime64('2012-06-30T20:00:00.000000000-0400')
  </code></pre>
  
  <p>Into:</p>
  
  <pre><code>'2012.07.01' as a  string. (note time difference)
  </code></pre>
  
  <p>I have already tried to convert the <code>datetime64</code> object to a <code>datetime</code> long then to a string, but I seem to get this error:</p>
  
  <pre><code>dt = t.astype(datetime.datetime) #1341100800000000000L
  time.ctime(dt)
  ValueError: unconvertible time
  </code></pre>