title: Numpy append to an empty array
body: <p>1st case :</p>
  
  <pre><code>&gt;&gt;&gt; import numpy as np
  &gt;&gt;&gt; x=np.array(0)
  &gt;&gt;&gt; x=np.append(x,1)
  &gt;&gt;&gt; x
  array([0, 1])
  </code></pre>
  
  <p><code>x</code> contains 2 elements. Why is that ?!</p>
  
  <p>2nd case :</p>
  
  <pre><code>&gt;&gt;&gt; x=np.array([])
  &gt;&gt;&gt; x=np.append(x,1)
  &gt;&gt;&gt; x
  array([ 1.])
  </code></pre>
  
  <p><code>x</code> contains 1 element, as expected.</p>
  
  <p>What's the difference between <code>np.array(0)</code> and <code>np.array([])</code> ?</p>