def ioa(boxlist1, boxlist2, scope=None):
  """Computes pairwise intersection-over-area between box collections.

  intersection-over-area (IOA) between two boxes box1 and box2 is defined as
  their intersection area over box2's area. Note that ioa is not symmetric,
  that is, ioa(box1, box2) != ioa(box2, box1).

  Args:
    boxlist1: BoxList holding N boxes
    boxlist2: BoxList holding M boxes
    scope: name scope.

  Returns:
    a tensor with shape [N, M] representing pairwise ioa scores.
  """
  with tf.name_scope(scope, 'IOA'):
    intersections = intersection(boxlist1, boxlist2)
    areas = tf.expand_dims(area(boxlist2), 0)
    return tf.truediv(intersections, areas)
Computes pairwise intersection-over-area between box collections.

  intersection-over-area (IOA) between two boxes box1 and box2 is defined as
  their intersection area over box2's area. Note that ioa is not symmetric,
  that is, ioa(box1, box2) != ioa(box2, box1).

  Args:
    boxlist1: BoxList holding N boxes
    boxlist2: BoxList holding M boxes
    scope: name scope.

  Returns:
    a tensor with shape [N, M] representing pairwise ioa scores.
  
inference_api/src/main/object_detection/core/box_list_ops.py