title: Is there something like a "placeholder" as element in arrays in numpy?
body: <p>I have a certain numpy 1d - array with a fixed number of elements with which I am doing some mathematical operations. When one of the elements becomes zero, I want to delete it, but instead of making the size of the 1d - array smaller, I need to fill temporarily with a placeholder. By placeholder, I mean something that it will determine in the future that the next element will be put in this specific position and not at the end of the array.</p>
  
  <p>Specifically what I am doing now is the following:</p>
  
  <pre><code>delete_ind = np.where(element == 0)[0]
  array = np.delete(array, delete_ind)
  
  ...
  
  array = np.append(array, new_element)
  </code></pre>
  
  <p>But this shifts the values to the left, while I want to fill the delete_ind with blank and then go back and put in the blank position the new_element.</p>