def jaccard_overlap(pred, gt, is_bbox_normalized=False):
    """
    Calculate jaccard overlap ratio between two bounding box
    """
    if pred[0] >= gt[2] or pred[2] <= gt[0] or \
        pred[1] >= gt[3] or pred[3] <= gt[1]:
        return 0.
    inter_xmin = max(pred[0], gt[0])
    inter_ymin = max(pred[1], gt[1])
    inter_xmax = min(pred[2], gt[2])
    inter_ymax = min(pred[3], gt[3])
    inter_size = bbox_area([inter_xmin, inter_ymin, inter_xmax, inter_ymax],
                           is_bbox_normalized)
    pred_size = bbox_area(pred, is_bbox_normalized)
    gt_size = bbox_area(gt, is_bbox_normalized)
    overlap = float(inter_size) / (pred_size + gt_size - inter_size)
    return overlap

    Calculate jaccard overlap ratio between two bounding box
    
ppdet/metrics/map_utils.py