def get_field(self, field):
    """Accesses data associated with the specified field in the box collection.

    Args:
      field: a string parameter used to speficy a related field to be accessed.

    Returns:
      a numpy 1-d array representing data of an associated field

    Raises:
      ValueError: if invalid field
    """
    if not self.has_field(field):
      raise ValueError('field {} does not exist'.format(field))
    return self.data[field]
Accesses data associated with the specified field in the box collection.

    Args:
      field: a string parameter used to speficy a related field to be accessed.

    Returns:
      a numpy 1-d array representing data of an associated field

    Raises:
      ValueError: if invalid field
    
inference_api/src/main/object_detection/utils/np_box_list.py