title: Creating a dynamic array using numpy in python
body: <p>I want to create a dynamic array without size specification. In that array, I need to insert elements at any point I require. The remaining values in them can be either null or undefined till it gets a value assigned to it.</p>
  
  <p>Ex:</p>
  
  <pre><code>a = np.array([])
  
  np.insert(a, any index value, value)
  </code></pre>
  
  <p>So, if I use <code>np.insert(a, 5, 1)</code> I should get the result as:</p>
  
  <pre><code>array([null, null, null, null, null, 1])
  </code></pre>