title: Is there a library function for Root mean square error (RMSE) in python?
body: <p>I know I could implement a root mean squared error function like this:</p>
  
  <pre><code>def rmse(predictions, targets):
      return np.sqrt(((predictions - targets) ** 2).mean())
  </code></pre>
  
  <p>What I'm looking for if this rmse function is implemented in a library somewhere, perhaps in scipy or scikit-learn?</p>