title: Efficient copying of source array to destination array via boolean mask
body: <p>I have a pair of 2-d arrays of the same size, source array and destination array. Source array also has an identically sized boolean array filled with a random mixture of True/False values. I want to copy over the source cells that correspond to "True" values in the boolean array into the equivalent locations in the destination array, overwriting those specific destination values.</p>
  
  <p>There's got to be a better way to do this than by slowly for-looping my way across the entire source array, checking against the boolean array, and overwriting individual values in the destination.</p>
  
  <p><a href="https://i.stack.imgur.com/g6fcV.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/g6fcV.png" alt="Sample"></a></p>