title: vectorized way to change numpy array values based on another array
body: <p>Is there is a vectorized (or better) way of setting values to certain 
  data points of numpy array based on another way other than this way?</p>
  
  <pre><code>import numpy as np
  
  data = np.array([[1, 2, 3], [4, 5, 6], [7, 8, 9]])
  pos = np.array([[1, 2], [2, 0]])
  
  for p in pos:
      i,j = p
      data[i,j] = 20
  
  print(data)
  </code></pre>