title: Append an the entire array as one element to another array that has arrays of different sizes inside with Python
body: <p>Let's say I have array 'a' like this</p>
  
  <pre><code>&gt;&gt;&gt; a = np.array([[1,2], [3,4,5]])
  
  &gt;&gt;&gt; a.shape
  
  (2,)
  &gt;&gt;&gt; 
  </code></pre>
  
  <p>Now I'd like to append the entire of an array like [6,7,8,9] to it as just one element and not four:</p>
  
  <pre><code>&gt;&gt;&gt; b = np.append(a,[6,7,8,9])
  
  &gt;&gt;&gt; b.shape
  
  (6,)
  &gt;&gt;&gt; 
  </code></pre>
  
  <p>But this is not what I want. What I do want is to have b having 3 elements and not 6 by stacking every element of the new array to a. I found a workaround  this as below but what is the proper way to get this done?</p>
  
  <pre><code>&gt;&gt;&gt; b = np.append(a,[0])
  
  &gt;&gt;&gt; b[2] = [6,7,8,9]
  
  &gt;&gt;&gt; b.shape
  
  (3,)
  &gt;&gt;&gt; 
  </code></pre>