code: def continuous_frequency(self, data_frame):
          
          tap_timestamps = data_frame.td[data_frame.action_type==1]
          cont_freq = 1.0/(np.array(tap_timestamps[1:-1])-np.array(tap_timestamps[0:-2]))
          duration = math.ceil(data_frame.td[-1])
  
          return cont_freq, duration
docs: This method returns continuous frequency
  
              :param data_frame: the data frame
              :type data_frame: pandas.DataFrame
              :return cont_freq: frequency
              :rtype cont_freq: float