class_docstr: Assign ground truth bounding boxes to given RoIs.
  
  The :meth:`__call__` of this class generates training targets
  for each object proposal.
  This is used to train Faster RCNN [#]_.
  
  .. [#] Shaoqing Ren, Kaiming He, Ross Girshick, Jian Sun.     Faster R-CNN: Towards Real-Time Object Detection with     Region Proposal Networks. NIPS 2015.
  
  Args:
      n_sample (int): The number of sampled regions.
      pos_ratio (float): Fraction of regions that is labeled as a
          foreground.
      pos_iou_thresh (float): IoU threshold for a RoI to be considered as a
          foreground.
      neg_iou_thresh_hi (float): RoI is considered to be the background
          if IoU is in
          [:obj:`neg_iou_thresh_lo`, :obj:`neg_iou_thresh_hi`).
      neg_iou_thresh_lo (float): See above.
code: def __init__(
      self,
      n_sample=128,
      pos_ratio=0.25,
      pos_iou_thresh=0.5,
      neg_iou_thresh_hi=0.5,
      neg_iou_thresh_lo=0.0,
  ):
      self.n_sample = n_sample
      self.pos_ratio = pos_ratio
      self.pos_iou_thresh = pos_iou_thresh
      self.neg_iou_thresh_hi = neg_iou_thresh_hi
      self.neg_iou_thresh_lo = neg_iou_thresh_lo
  
file_path: chainercv/chainercv/links/model/faster_rcnn/utils/proposal_target_creator.py
imports: import numpy
  from chainer.backends import cuda
  from chainercv.links.model.faster_rcnn.utils.bbox2loc import bbox2loc
  from chainercv.utils.bbox.bbox_iou import bbox_iou
label_desc: Use image node_id 1 to create a new ProposalTargetCreator object from inherited base classes: object with example: obj = ProposalTargetCreator(n_sample, pos_ratio, pos_iou_thresh, neg_iou_thresh_hi, neg_iou_thresh_lo)