title: numpy.concatencate two same size row vector to matrix
body: <pre><code>a=np.random.uniform(0,1,10)
  b=np.random.uniform(0,1,10)
  a=np.concatenate(a,b, axis=0)
  </code></pre>
  
  <p>I am refresh <code>a</code> to be <code>(2x10)</code> matrix. But what I got was just an <code>(1x20)</code> array. </p>
  
  <p>The example works well.</p>
  
  <pre><code>a = np.array([[1, 2], [3, 4]])
  b = np.array([[5, 6]])
  np.concatenate((a, b), axis=0)
  </code></pre>
  
  <p>gives</p>
  
  <pre><code>array([[1, 2],
     [3, 4],
     [5, 6]])
  </code></pre>
  
  <p>Why? And what can I do to change this?</p>
  
  <p>Thank you and the editor.</p>