title: why setting dtype on numpy array changes dimensions?
body: <p>I am tryng to understand how to set dtypes of an array. My original numpy array dimensions are (583760, 7) i.e. 583760 rows and 7 columns. I am setting dtype as follows</p>
  
  <pre><code>&gt;&gt;&gt; allRics.shape
  (583760, 7)
  &gt;&gt;&gt; allRics.dtype = [('idx', np.float), ('opened', np.float), ('time', np.float),('trdp1',np.float),('trdp0',np.float),('dt',np.float),('value',np.float)]
  &gt;&gt;&gt; allRics.shape
  (583760, 1)
  </code></pre>
  
  <p>Why is there a change in the original shape of the array? What causes this change? I am basically trying to sort original numpy array by <code>time</code> column and thats why I am setting the <code>dtype</code>. But after the dimension change, I am not able to sort array</p>
  
  <pre><code>&gt;&gt;&gt; x=np.sort(allRics,order='time')
  </code></pre>
  
  <p>there is no change in the output of the above command. Could you please advice?</p>