title: numpy dot product with missing values
body: <p>How do you do a numpy dot product where the two vectors might have missing values? This seems to require many additional steps, is there an easier way to do this?:</p>
  
  <pre><code>v1 = np.array([1,4,2,np.nan,3])
  v2 = np.array([np.nan,np.nan,2,4,1])
  np.where(np.isnan(v1),0,v1).dot(np.where(np.isnan(v2),0,v2))
  </code></pre>