code: def _friends_leaveoneout_radius(points, ftype):
      
  
      # Construct KDTree to enable quick nearest-neighbor lookup for
      # our resampled objects.
      kdtree = spatial.KDTree(points)
  
      if ftype == 'balls':
          # Compute radius to two nearest neighbors (self + neighbor).
          dists, ids = kdtree.query(points, k=2, eps=0, p=2)
      elif ftype == 'cubes':
          # Compute half-side-length to two nearest neighbors (self + neighbor).
          dists, ids = kdtree.query(points, k=2, eps=0, p=np.inf)
  
      dist = dists[:, 1]  # distances to LOO nearest neighbor
  
      return dist
docs: Internal method used to compute the radius (half-side-length) for each
      ball (cube) used in :class:`RadFriends` (:class:`SupFriends`) using
      leave-one-out (LOO) cross-validation.