code: def normalize(self, method='percentile', window=None, perc=20, offset=0.1):
          
  
          check_options(method, ['mean', 'percentile', 'window', 'window-exact'])
  
          from warnings import warn
          if not (method == 'window' or method == 'window-exact') and window is not None:
              warn('Setting window without using method "window" has no effect')
  
          if method == 'mean':
              baseFunc = mean
  
          if method == 'percentile':
              baseFunc = lambda x: percentile(x, perc)
  
          if method == 'window':
              from scipy.ndimage.filters import percentile_filter
              baseFunc = lambda x: percentile_filter(x.astype(float64), perc, window, mode='nearest')
  
          if method == 'window-exact':
              if window & 0x1:
                  left, right = (ceil(window/2), ceil(window/2) + 1)
              else:
                  left, right = (window/2, window/2)
  
              n = len(self.index)
              baseFunc = lambda x: asarray([percentile(x[max(ix-left, 0):min(ix+right+1, n)], perc)
                                            for ix in arange(0, n)])
  
          def get(y):
              b = baseFunc(y)
              return (y - b) / (b + offset)
  
          return self.map(get)
docs: Normalize by subtracting and dividing by a baseline.
  
          Baseline can be derived from a global mean or percentile,
          or a smoothed percentile estimated within a rolling window.
          Windowed baselines may only be well-defined for
          temporal series data.
  
          Parameters
          ----------
          baseline : str, optional, default = 'percentile'
              Quantity to use as the baseline, options are 'mean', 'percentile',
              'window', or 'window-exact'.
  
          window : int, optional, default = 6
              Size of window for baseline estimation,
              for 'window' and 'window-exact' baseline only.
  
          perc : int, optional, default = 20
              Percentile value to use, for 'percentile',
              'window', or 'window-exact' baseline only.
  
          offset : float, optional, default = 0.1
               Scalar added to baseline during division to avoid division by 0.