code: def point_within_radius(self, points, pt, canvas_radius,
                              scales=(1.0, 1.0)):
          
          scale_x, scale_y = scales
          x, y = pt
          a_arr, b_arr = np.asarray(points).T
          dx = np.fabs(x - a_arr) * scale_x
          dy = np.fabs(y - b_arr) * scale_y
          new_radius = np.sqrt(dx**2 + dy**2)
          res = (new_radius <= canvas_radius)
          return res
docs: Points `points` and point `pt` are in data coordinates.
          Return True for points within the circle defined by
          a center at point `pt` and within canvas_radius.