title: convert a tensorflow method in a pandas way, timestamp turn in seconde float
body: <p>I found this code and want to do it outside tensorflow with pandas:</p>
  <pre><code># Convert `Date Time` column into timestamps in seconds (using tfa helper function)
  timestamp_s = tfa.text.parse_time(outputs['Date Time'], time_format='%d.%m.%Y %H:%M:%S', output_unit='SECOND')
  timestamp_s = tf.cast(timestamp_s, tf.float32)
  </code></pre>
  <p>I did some try... all worst than the last one...</p>
  <p>The objective is to turn timestamp to vector for machine learning feature</p>