code: def R_r(self, r):
          
          phi = np.random.uniform(0, 2*np.pi)
          theta = np.random.uniform(0, np.pi)
          x = r * np.sin(theta) * np.cos(phi)
          y = r * np.sin(theta) * np.sin(phi)
          R = np.sqrt(x**2 + y**2)
          return R, x, y
docs: draws a random projection from radius r in 2d and 1d
          :param r: 3d radius
          :return: R, x, y