title: Deleting elements from numpy array with iteration
body: <p>What is the fastest method to delete elements from numpy array while retreiving their initial positions. The following code does not return all elements that it should:</p>
  
  <pre><code>list = []
  for pos,i in enumerate(ARRAY):
      if i &lt; some_condition:
          list.append(pos)  #This is where the loop fails
  
  for _ in list:
      ARRAY = np.delete(ARRAY, _)
  </code></pre>