title: Python: Create structured numpy structured array from two columns in a DataFrame
body: <p>How do you create a structured array from two columns in a DataFrame?
  I tried this:</p>
  
  <pre><code>df = pd.DataFrame(data=[[1,2],[10,20]], columns=['a','b'])
  df
  
      a   b
  0   1   2
  1   10  20
  
  x = np.array([([val for val in list(df['a'])],
                 [val for val in list(df['b'])])])
  </code></pre>
  
  <p>But this gives me this:</p>
  
  <pre><code>array([[[ 1, 10],
          [ 2, 20]]])
  </code></pre>
  
  <p>But I wanted this:</p>
  
  <pre><code>[(1,2),(10,20)]
  </code></pre>
  
  <p>Thanks!</p>