title: numpy.genfromtxt produces array of what looks like tuples, not a 2D array—why?
body: <p>I'm running <code>genfromtxt</code> like below:</p>
  
  <pre><code>date_conv = lambda x: str(x).replace(":", "/")
  time_conv = lambda x: str(x)
  
  a = np.genfromtxt(input.txt, delimiter=',', skip_header=4,
        usecols=[0, 1] + radii_indices, converters={0: date_conv, 1: time_conv})
  </code></pre>
  
  <p>Where <code>input.txt</code> is from <a href="https://gist.github.com/1958483" rel="noreferrer">this gist</a>.</p>
  
  <p>When I look at the results, it is a 1D array not a 2D array:</p>
  
  <pre><code>&gt;&gt;&gt; np.shape(a)
  (918,)
  </code></pre>
  
  <p>It seems to be an array of tuples instead:</p>
  
  <pre><code>&gt;&gt;&gt; a[0]
  ('06/03/2006', '08:27:23', 6.4e-05, 0.000336, 0.001168, 0.002716, 0.004274, 0.004658, 0.003756, 0.002697, 0.002257, 0.002566, 0.003522, 0.004471, 0.00492, 0.005602, 0.006956, 0.008442, 0.008784, 0.006976, 0.003917, 0.001494, 0.000379, 6.4e-05)
  </code></pre>
  
  <p>If I remove the converters specification from the <code>genfromtxt</code> call it works fine and produces a 2D array:</p>
  
  <pre><code>&gt;&gt;&gt; np.shape(a)
  (918, 24)
  </code></pre>