code: def extract(self):
          
  
          # the sample values themselves are kept cached to prevent
          # multiple calls to the integrator code.
          if self.values is not None:
              return self.values
          else:
              s = self._extract()
              self.values = s
              return s
docs: Extract sample data by scanning an elliptical path over the
          image array.
  
          Returns
          -------
          result : 2D `~numpy.ndarray`
              The rows of the array contain the angles, radii, and
              extracted intensity values, respectively.