code: def frequency(self, data_frame):
          
          freq = sum(data_frame.action_type == 1) / data_frame.td[-1]
          duration = math.ceil(data_frame.td[-1])
  
          return freq, duration
docs: This method returns the number of #taps divided by the test duration
  
              :param data_frame: the data frame
              :type data_frame: pandas.DataFrame
              :return frequency: frequency
              :rtype frequency: float