code: def iou_distance(atracks, btracks):
      """
      Compute cost based on IoU between two list[STrack].
      """
      if (len(atracks) > 0 and isinstance(atracks[0], np.ndarray)) or (
          len(btracks) > 0 and isinstance(btracks[0], np.ndarray)
      ):
          atlbrs = atracks
          btlbrs = btracks
      else:
          atlbrs = [track.tlbr for track in atracks]
          btlbrs = [track.tlbr for track in btracks]
      _ious = bbox_ious(atlbrs, btlbrs)
      cost_matrix = 1 - _ious
  
      return cost_matrix
  
file_path: PaddleDetection/ppdet/modeling/mot/matching/jde_matching.py
imports: import scipy
  import numpy
  from scipy.spatial.distance import cdist
  from ..motion import kalman_filter
  import warnings
label_desc: Use image node_id 4 for calling a global function with example usage: iou_distance(atracks, btracks) and returns: cost_matrix