code: def resample_data(self, data, freq, resampler='mean'):
          
  
          if resampler == 'mean':
              data = data.resample(freq).mean()
          elif resampler == 'max':
              data = data.resample(freq).max()
          else:
              raise ValueError('Resampler can be \'mean\' or \'max\' only.')
          
          return data
docs: Resample dataframe.
  
          Note
          ----
          1. Figure out how to apply different functions to different columns .apply()
          2. This theoretically work in upsampling too, check docs
              http://pandas.pydata.org/pandas-docs/stable/generated/pandas.DataFrame.resample.html 
  
          Parameters
          ----------
          data        : pd.DataFrame()
              Dataframe to resample
          freq        : str
              Resampling frequency i.e. d, h, 15T...
          resampler   : str
              Resampling type i.e. mean, max.
  
          Returns
          -------
          pd.DataFrame()
              Dataframe containing resampled data