title: Keras find index by vectors - Reverse embedding layer
body: <p>Simple question.
  When using Embedding layer from keras, it would go like this</p>
  
  <pre><code>[index, index, index,...,index] -&gt; [[vec], [vec], [vec]...,[vec]]
  </code></pre>
  
  <p>where index is some integer number and vec is vector.</p>
  
  <p>Now suppose if I have vectors. How can I get index from these vectors? Does Keras support using it in FC network Model?</p>