title: Python: turn single array of sorted, repeat values into an array of arrays?
body: <p>I have a sorted array with some repeated values.  How can this array be turned into an array of arrays with the subarrays grouped by value (see below)? In actuality, my_first_array has ~8 million entries, so the solution would preferably be as time efficient as possible.</p>
  
  <pre><code>my_first_array = [1,1,1,3,5,5,9,9,9,9,9,10,23,23]
  
  wanted_array = [ [1,1,1], [3], [5,5], [9,9,9,9,9], [10], [23,23] ]
  </code></pre>