title: Keras custom decision threshold for precision and recall
body: <p>I'm doing a binary classification using <code>Keras</code> (with <code>Tensorflow</code> backend) and I've got about 76% precision and 70% recall. Now I want to try to play with decision threshold. As far as I know <code>Keras</code> uses decision threshold 0.5. Is there a way in <code>Keras</code> to use custom threshold for decision precision and recall?</p>
  
  <p>Thank you for your time!</p>