title: what's the mean of "reshape(-1,1,2)"
body: <pre><code>x = np.linspace(0,10, 5)
  y = 2*x
  points = np.array([x, y]).T.reshape(-1, 1, 2)
  </code></pre>
  
  <p>What's the mean of the third line?I know the mean of <code>reshape(m,n)</code>, but what does <code>reshape(-1, 1, 2)</code> means?</p>