title: How to add a constant value to every other column in a numpy array?
body: <p>I am having trouble adding a constant value to every other column in a numpy array. For example, Let's say that I have an array of zeros like:</p>
  <pre><code>import numpy as np    
  a = np.zeros([100,10], dtype=np.int64)
  </code></pre>
  <p>and now I want to add a constant, say '50', to every element in every other column. This way I would expect to keep an array that is 10 columns by 100 rows that alternates as 0,50,0,50,0,50... etc</p>