code: def convert_mapper(self, tomap):
          
          frommap = self.crdmap
          if frommap == tomap:
              return
  
          # mild hack to convert radii on objects that have them
          if hasattr(self, 'radius'):
              # get coordinates of a point radius away from center
              # under current coordmap
              x0, y0 = frommap.offset_pt((self.x, self.y), (self.radius, 0))
              pts = frommap.to_data(((self.x, self.y), (x0, y0)))
              pts = tomap.data_to(pts)
              self.radius = np.fabs(pts[1][0] - pts[0][0])
  
          elif hasattr(self, 'xradius'):
              # similar to above case, but there are 2 radii
              x0, y0 = frommap.offset_pt((self.x, self.y), (self.xradius,
                                                            self.yradius))
              pts = frommap.to_data(((self.x, self.y), (x0, y0)))
              pts = tomap.data_to(pts)
              self.xradius = np.fabs(pts[1][0] - pts[0][0])
              self.yradius = np.fabs(pts[1][1] - pts[0][1])
  
          data_pts = self.get_data_points()
  
          # set our map to the new map
          self.crdmap = tomap
  
          self.set_data_points(data_pts)
docs: Converts our object from using one coordinate map to another.
  
          NOTE: In some cases this only approximately preserves the
          equivalent point values when transforming between coordinate
          spaces.