title: Python: numpy loadtxt with integer and datetime
body: <p>I don't understand how works the loadtxt methode of numpy. I have read some questions/answers on the website but it's not clear for me.</p>
  
  <p>I have a file 'data.txt' which is :</p>
  
  <pre><code>WEIGHT,DAY
  75.1,16/10/2018
  75.2,17/10/2018
  ...
  </code></pre>
  
  <p>My code is :</p>
  
  <pre><code>def parsetime(v):
      print(type(v))
      print(v)
      return np.datetime64(
          datetime.strptime(v, '%d/%m/%Y')
      )
  
  data = np.loadtxt('masse.txt',delimiter=',',usecols=(0, 1),converters = {1:parsetime},skiprows=1)
  </code></pre>
  
  <p>But it doesn't work correctly cause it's giving to the function parsetime a byte and not a string...</p>
  
  <pre><code>&lt;class 'bytes'&gt; 
  b'16/10/2018'
  </code></pre>
  
  <p>I just want an np.array which has in first column an integer and the second column a date.</p>
  
  <p>I'am a bit lost.
  Thanks a lot by advance,</p>